- Flight Planning Issues
- Safety Management Enhances Safety in Gliding Clubs
- Near Collision on Runway 08R at Vancouver
- Say Again! Communication Problems Between Controllers and Pilots
- Checklist Actions After Engine Failure on Takeoff
- Computers in Aviation: Friend or Foe?
"Aviate-navigate-communicate." This time-honoured axiom continues to be as relevant and instructive today as when it was first coined many decades ago. It succinctly sums up in three words the tasking priorities that are essential for a pilot to successfully handle any non-routine situation or occurrence. These priorities are equally applicable for all aircraft, from small, single-engine training aircraft, right up to large, transport category jets. This expression may have been coined in the early days by an enlightened (or frustrated) flight instructor in a J-3 Cub or Fleet Canuck, but it is more applicable than ever for the pilots of today's automated aircraft.
A distraction can divert the pilot's attention from primary tasks
It is easy to determine how distractions can occur in a single-pilot aircraft. The Federal Aviation Administration (FAA) determined, "that stall/spin related accidents accounted for approximately one-quarter of all fatal general aviation accidents. National Transportation Safety Board [NTSB] statistics indicate that most stall/spin accidents result when a pilot is distracted momentarily from the primary task of flying the aircraft."1
One of the first things that we learn as fledgling pilots is that improper airspeed management can lead to a stall. Nevertheless, data gathered from accident/incident investigations clearly shows how easily a stall can occur to experienced pilots who are distracted by one or more other tasks. Distractions can be almost anything- even some tasks considered routine-during normal operations: locating a checklist, retrieving something from behind your seat, looking up a frequency or other aeronautical data, or becoming engrossed in navigation calculations. The list is almost endless. These actions all have the potential to divert a pilot from the primary task of flying the aircraft.
The obvious conclusion is that learning how to prioritize effectively and not succumb to distractions is a tremendously important skill. "Through training and experience, you can learn to discipline your attention mechanisms so as to focus on important items."2 Unfortunately, in the current environment, maintaining effective priorities and avoiding distractions is not getting easier. Recent innovations like global positioning system (GPS) navigation and electronic flight instrument systems (EFIS) have brought tremendous sophistication to modern general aviation aircraft. But the latest avionics have also brought new potential hazards for pilots. In this environment, it is all too easy for the pilot to "remain heads down" for far too long. It is also possible for a pilot to become complacent and overly dependant on automated systems. This can cause the deterioration of basic skills.
The problem of distractions also exists in multi-crew aircraft. In this environment, the pilot flying (PF) must focus on flying the aircraft and must guard against allowing too much of his attention to be diverted by the tasks being performed by the pilot not flying (PNF). An excellent example of the consequences of distraction is the L-1011 that crashed into the Florida Everglades, killing 99 OF 176 souls on board. The NTSB, "cited as a causal factor the diversion of the crew's attention to a burned out light bulb. The crew had been so intent on the bulb that they had not noticed the descent of their aircraft nor had they heard various alarms warning of their closeness to the ground."3
New technologies have created new opportunities for pilots to be distracted. The programming of the flight management system (FMS), or completion of an electronic checklist can lure the PF away from their primary task. It is all too easy for the electronic displays to divert one's attention. Remember that the various electronic displays can act like "face magnets." Make sure that you maintain situational awareness and don't allow yourself to get sidetracked.
A recent incident illustrated how easily distractions can result in improper airspeed management with serious consequences. The crew of a transport category jet was flying at flight level (FL) 400 and had been diverted west of their planned route. The pilot reduced thrust to slow the aircraft in anticipation of traffic delays. "The captain then focused attention to the flight management system (FMS) on the centre console to help the first officer determine fuel reserves for a possible hold."4 While both members of the crew were occupied with the fuel calculations for a possible hold, the airspeed decreased and the stick shaker activated. "Both pilots pushed the control yoke forward to reduce the pitch attitude, which resulted in a descent and an increase in airspeed. This was followed by the crew returning the aircraft to a pitch-up attitude, with an increase in body angle of attack (AOA) and G. (Author's note: For bodies undergoing acceleration and deceleration, G is used as a unit of load measurement.) A second stick shaker activation occurred 11 seconds after the first. Buffeting and roll oscillations of about 10° accompanied the stick shaker events. The pitch attitude was further reduced and the airspeed recovered [...] The altitude stabilized briefly at FL 386 before the crew coordinated with ATC for a further descent to FL 380 due to conflicting traffic."5
Fortunately, there was no damage to the aircraft, or injuries to passengers or crew, and the flight landed safely without further incident. Had there been traffic below this aircraft, or had a similar airspeed mismanagement and approach to stall occurred close to the ground, the consequences may have been catastrophic. Incidents such as this serve to remind all of us of the need to focus on the essential priorities: "aviate-navigate-communicate."
To help us understand the critically important roles of the PF and PNF, let's review how the modern flight deck of a transport category aircraft evolved. In the last 60 years, from the post-war boom in air transportation until today, transport category aircraft have seen tremendous increases in their complexity, performance capabilities and size. At the same time, technological innovations have steadily reduced the number of flight crew members.
In the 1940s, an aircraft like the Boeing Stratocruiser would typically accommodate as many as 81 passengers and would cruise at 280 kt. Today, an A 340 can carry more than 300 passengers and will cruise at 470 kt. The flight crew of a Stratocruiser consisted of five members: a radio operator, a navigator, a flight engineer, and two pilots. As the years progressed, improvements in electronics resulted in the radio operator no longer being needed. Long range navigation systems like inertial navigation systems (INS) eventually made navigators unnecessary. Ultimately, the two-pilot flight deck emerged during the early 1980s, when increases in system automation eliminated the need for a flight engineer. Today, virtually all transport category aircraft have only two pilots.
Photo of Boeing Stratocruiser courtesy of www.aviation-history.com, with permission.
Copyright Airbus; photographer H. Goussé.
Transport category aircraft have seen tremendous increases in their complexity, performance capabilities and size.
At the same time, technological innovations have steadily reduced the number of flight crew members.
Copyright Airbus; photographer H. Goussé.
Modern two-crew flight deck
The two-crew flight deck brings certain challenges, which are especially apparent during periods of high workload. Depending on the circumstances, the PNF may also need to perform the functions of one of the crew members that was eliminated by advances in technology. For example, when an aircraft is being re-routed and it is necessary to calculate fuel reserves, the PNF takes on the responsibilities that were previously those of the navigator.
If an abnormal or emergency situation occurs, the PNF completes the appropriate checklists and essentially performs the tasks of a flight engineer. A problem can arise when the PF depends on automation and becomes overly involved in the PNF's activities. Adhering to the correct priorities will ensure that one crew member always focuses on flying the aircraft.
Simulators provide an outstanding tool for learning. In the simulator, we can safely gain first-hand experience with windshear, catastrophic engine failures, jammed flight controls, as well as losses of electrical and hydraulic power; things that we would never want to experience in a real aircraft. In addition to learning about technical issues, the simulator provides a powerful tool for learning about human factors. The simulator provides an excellent opportunity for us to learn the essential skill of prioritizing.
The primary task of flying the aircraft can never become secondary. There is nothing more important. Ultimately, we need to remain focused and maintain our priorities: "aviate – navigate – communicate".
Prior to joining Transport Canada, Captain Kostecka worked as a pilot and instructor for several Canadian airlines. He has flown over 12 000 hr and holds a Class 1 Flight Instructor Rating as well as type ratings on the A320, A330, A340, B757, B767, CRJ, DHC-8 and B-25.
1 FAA Advisory Circular No. AC 61-67B, Subject: Stall and Spin Awareness Training, p. ii
2 Human Factors for Aviation-Basic Handbook (TP 12863), p. 38
3 Human Factors for Aviation-Basic Handbook (TP 12863), p. 37
4 Transportation Safety Board of Canada (TSB) Aviation Investigation Report A05W0109, p. 2
5 Transportation Safety Board of Canada (TSB) Aviation Investigation Report A05W0109, p. 3
On page 29 of Aviation Safety Letter (ASL) 3/2006, Michael Oxner provided an excellent article on how VFR pilots can benefit from the use of "flight following" while flying in Canada. The air traffic services (ATS) system also provides an additional service by keeping an eye on the status or location of pilots who have filed a proposed flight plan. This is done in case an aircraft is overdue and it becomes necessary to alert the Canadian Armed Forces rescue coordination centre (RCC). Let's call this activity search and rescue (SAR) tracking.
While the treatment of IFR and VFR flight plans have many similarities, there are some differences. This article will address VFR flight plan activities.
The vast majority of pilots perform the correct actions regarding VFR flight plans; however, there are some pilots who are causing unnecessary workloads and occasionally misusing very scarce resources because they do not understand (or completely ignore) the proper procedures for opening, amending or closing VFR flight plans. Therefore, it would seem to be a good idea to review what should take place when a pilot files a VFR flight plan.
To begin, the pilot submits a VFR flight plan that contains a proposed time of departure and an estimated elapsed time en route. In Canada, and many parts of the world, the ATS system will begin SAR tracking based on the proposed departure time-this is done because there are circumstances under which the pilot departs from a remote location and the ATS system will not know the actual time of departure. This is the beginning of the safety net.
This differs from the United States, where the Federal Aviation Administration (FAA) does not start SAR tracking unless the pilot activates the flight plan on departure. Note that in Canada, the SAR tracking for a VFR flight plan will continue from the proposed departure time until a specified time, or one hour after the estimated time of arrival (ETA). At this prescribed time, if the location of the flight is unknown, the airplane is reported missing and a search for the "missing" airplane begins. Canadian Armed Forces RCCs, at various locations across Canada, are notified of the missing aircraft.
In some instances, SAR aircraft have been launched to look for a "missing" aircraft when, in fact, the pilot had decided not to fly the proposed trip and did not cancel, close, or report changes to the VFR flight plan.
Between February 2005, and February 2006, there were at least 96 incidents involving VFR flight plans. Problems arose for a variety of reasons. A breakdown of the incidents follows:
- 26 transborder flights arrived from the USA without a flight plan (the reasons are undetermined, but it may be that pilots failed to activate the VFR flight plan);
- 43 flights did not file an arrival report;
- 9 flights changed flight duration without notifying anyone;
- 3 flights filed flight plans by fax, but the pilot did not confirm receipt;
- 3 flights had pilots who changed aircraft without amending the flight plan; and
- 12 flights did not depart, and the pilot did not cancel the flight plan.
There may be good reasons for some of the errors noted above; however, it is very unlikely that every incident occurred for a good reason. Given that the Canadian topography and weather conditions can sometimes be quite harsh, I personally like the warm and fuzzy feeling I get from knowing that someone is watching over me who will alert an RCC in the event that I am forced to land or crash while en route and do not arrive at my destination at the scheduled time. Unfortunately, because of the scarcity of resources, it is possible that SAR aircraft would not be able to search for an actual downed airplane because they are looking for one or more of the "missing" aircraft described above.
We are very lucky in Canada to have an efficient and effective SAR tracking and activation service. In some countries, the cost of SAR activity is charged to the"missing" pilot-think about that!
Approximately one year ago, the Soaring Association of Canada (SAC) Board of Directors made the decision to implement a safety management system (SMS) at the national level. Although we have had a safety program in place for many years, an SMS would insert some additional safety-management methods; it would be based largely on the Transport Canada SMS for small operators. The SAC club programs or the implementation of a new program.
Workshops were run across the country last spring, at which point the program was introduced and the participants were taken through the process of hazard identification and risk assessment for typical club operations. Although there were some questions about the value of this program at the time, clubs have had a positive attitude regarding the need for improvements. Club representatives were asked to return to their clubs and involve members in these tasks, which include a requirement to define strategies to address and reduce or mitigate the identified risks. If you, as a reader of this Aviation Safety Letter (ASL), have not been involved at the club level, or are unaware of this program, now is the time to act-before you flex your wings again at the start of the new soaring season. Start thinking of how you can contribute to a safer club environment, and hence safer flying operation; ask about the club's safety program, and how you can take part.
It is too early to attribute the excellent safety record for gliding in 2006 to this program, but a heightened awareness of the need to remain vigilant about hazards may have played a part. Hazard identification is one of the first essential tasks of this safety initiative, followed by the design of a club strategy to reduce the safety risks. There can be hazards in the following areas: Administrative (lack of emergency procedures), Supervisory (at the flight line), the Safety Program (poor feedback of lessons learned), Airport/Airfield Infrastructure (public access/signage), Airport/Airfield (poor overshoot and undershoot areas, grass cutting), Pilots (recurrent training/checks, advanced/cross-country training), Pilot Experience (efforts/strategies to maintain currency levels), Weather Conditions (flight planning and preparation for the anticipated conditions). You can probably think of more. If not, look back on past incidents and learn from them.
The SAC SMS and safety program are in their early stages of development. The relevant documents are available on the SAC Web site at http://www.sac.ca/.
On October 29, 2004, a potentially catastrophic near collision occurred between a departing BN2P Islander and a taxiing Dash-8, on Runway 08R at the Vancouver International Airport. At 06:53 Pacific Daylight Time (PDT), the Vancouver tower south controller cleared the Islander for takeoff from the threshold of Runway 08R. The Islander was in the rotation for liftoff when it went by a Dash-8 that was partially on the runway, abeam the Islander's left wingtip, at Taxiway L2. The final report on this occurrence (TSB file A04P0397) was released on November 6, 2006.
Immediately prior to the occurrence, the tower controller had seven departing aircraft holding short for departure on Runway 08R and two on final. On the south side of the threshold, on Taxiway A (see illustration), was a BN2P Islander followed by a Mitsubishi MU-2. Opposite, on Taxiway L, was a Dash-8 followed by two more Islanders, and a second Dash-8. There was a third Dash-8 holding short of Runway 08R on L2. Taxiway L2 is also a high-speed exit for the reciprocal Runway 26L.
It was still dark; the visibility was 8 SM and improving. After the first Dash-8 on Taxiway L departed, the first arrival landed. The controller then cleared the Islander on Taxiway A to taxi to position and hold on Runway 08R and requested that the pilot move ahead to permit a Dash-8 to line up behind. The controller then cleared the Dash-8 (believed to be on Taxiway L) to take position behind the Islander, without realizing that the Dash-8 was down the runway at L2. Since the controller thought the Dash-8 and the Islander were both at the threshold of 08R, he did not state the specific entry point for either one, nor was he required to do so.
The Dash-8 crew at L2 apparently acknowledged their clearance to position; however, it was blocked by another transmission. The Dash-8 at L2 began taxiing toward Runway 08R, while looking ahead for the Islander it was to follow-which was in fact behind it.
After the blocked transmission, the controller asked who made the last call. A transmission came from "the Dash-8 behind the Islander," which matched the controller's mindset of the situation, but it was not the same Dash-8. A comment was made about the Islander's lights not working (there were still two more Islanders waiting to depart). A series of confusing and mostly unsolicited transmissions from unidentified sources took place regarding navigation lights on Islanders. It was during this series of transmissions that the Islander in position at the threshold of Runway 08R was cleared for takeoff and complied with that clearance.
As the Dash-8 at L2 was moving toward Runway 08R, the crew was still unable to see the Islander they were instructed to line-up behind, and became uneasy about the situation. The crew elected to turn the aircraft to their right, to look toward the threshold of 08R. They then saw the landing lights of the Islander coming down the runway on the take-off run. The crew stopped the Dash-8 and displayed all exterior aircraft lights as the Islander rotated in front of them.
Analysis-Following the routine pre-shift review and briefing, the controller was not aware that Taxiway L2 was open; on the controller's two previous night shifts, L2 had been closed for maintenance. When the controller scanned the departure flight progress strips for the taxiway designators assigned by the ground controller, it was not recognized that the digit "2" was partially obscured by other information for the one departure on Taxiway L2.
The airport control tower is equipped with airport surface detection equipment (ASDE). This ground surveillance radar system displays targets on the airport, but it has some inherent limitations and some unresolved technical anomalies. The tower controller did not rely on this system, and did not associate a target on Taxiway L2 with the Dash-8, or monitor the ASDE when the Dash-8 was cleared to position behind the Islander.
Prior to the incident, the controller was stating runway entry positions in all clearances onto the active Runway 08R, and these positions were being read back by flight crews. Although not a requirement for entry at the threshold, this appeared to be a common practice, but it ceased in the minutes leading up to this incident. In the specific take-off clearance leading to this occurrence, the controller did not state the runway entry position on 08R, nor did the Islander pilot voluntarily state it, which precluded the opportunity of alerting the Dash-8 at L2.
As a point of interest for all pilots departing from any entry location along a runway, controllers are required to specify the runway entry location at an intersection or taxiway other than at the threshold, which is mentioned in the Transport Canada Aeronautical Information Manual (TC AIM) RAC 4.2.5.
It is not a requirement for a pilot to read back or otherwise state their runway entry location; however, if pilots are aware of the controller's requirement, it would be reasonable to expect that a pilot would challenge the controller if the clearance onto a runway, not at the threshold, did not include the intersection name or taxiway location.
Therefore, in theory, the Dash-8 crew could have noticed the absence of this requirement in the controller's clearance to line-up on 08R when they were at Taxiway L2.
It has been a long-standing argument that a common frequency allows pilots to maintain better situational awareness. Numerous aircraft were tuned in to the Vancouver tower south frequency. No one advised the controller that there was no Dash-8 at the threshold able to line up behind the Islander. It is unknown why the sole pilot of the Islander did not see the Dash-8 at L2 taxiing onto the runway ahead.
Following this incident, the Vancouver tower implemented an operations bulletin to remind controllers of the requirement to specify the name of the taxiway or intersection when issuing a clearance to position or for takeoff, other than at the threshold, and further recommended that the procedure be applied to the threshold as well. In the immediate term, the TSB is working with NAV CANADA and Transport Canada to encourage good airmanship practices to supplement this air traffic control (ATC) requirement and enhance safety while more permanent requirements are being considered.
"Regardless of the level of sophistication that the air traffic system achieves by the turn of the century, the effectiveness of our system will always come down to how successfully we communicate."
Linter and Buckles, 1993
Voice communications between controllers and pilots are a vital part of air traffic control (ATC) operations. Miscommunication can result in hazardous situations. For instance, miscommunication has been identified as a primary factor causing runway incursions. The collision between two Boeing 747s at Tenerife in 1977, demonstrates the potentially fatal consequences of inadequate communication.
Each year, millions of transmissions are made between controllers and pilots. Most of these transmissions relate to instructions given by controllers, and the responses from the pilots to these instructions. Analysis of samples of pilot-controller communications recorded in different ATC centres revealed that some kind of miscommunication occurred in only 0.7 percent of all transmissions made. In more than half of these, the problems were detected and solved by the controller or pilot. These are very good numbers, considering the fact that at least two humans are involved in the communication process.
So what can go wrong? In order to answer this question, the National Aerospace Laboratory NLR conducted a study on air-ground communication problems, using recorded incidents in Europe. This study was commissioned by EUROCONTROL as part of their safety improvement initiative. Although this study was limited to the situation in Europe, many of the identified issues apply to other parts of the world (e.g. North America). The results of this study were published in two reports that can be obtained from EUROCONTROL (see the end of this article). This article will briefly discuss some of the important results from these studies.
The most typical communication problem identified was related to the so-called readback and hearback errors. These come in two flavours: one in which the pilot reads back the clearance incorrectly and the controller fails to correct the error (readback/hearback error), and the other in which the controller fails to notice his or her own error in the pilot's correct readback or fails to correct critical erroneous information in a pilot's statement of intent. The following is an example of a typical readback/hearback error: "the B737 was outbound from XX maintaining 6 000 ft. The Tu154 was outbound from YY, and on initial call to the KK sector, was cleared to 5 000 ft. However, the pilot read back the clearance as 6 000 ft, which was unnoticed by the controller. A short term conflict alert (STCA) warned the controller of the situation, and avoiding action was issued to both aircraft." An example that illustrates a hearback error is the following: "the aircraft was cleared to descend to FL 150, but acknowledged a descent to FL 180. This was challenged by the controller, who then inadvertently cleared the aircraft to FL 130. This incorrect flight level was read back by the pilot, and was not corrected by the controller." Other typical problems found, were related to cases where there was a complete loss of communication, or there were problems with the communication equipment on the ground or in the aircraft itself. An example of loss of communications is the following: "a B777 was transferred from frequency 129.22 to the XX sector frequency, 134.77, and readback appeared to be correct. Approximately 5 min later, the XX sector controller telephoned to ask for the B777 to be transferred, and was informed that it had been. Subsequently, the B777 called frequency 129.22 to advise of having gone to the wrong frequency. The B777 was absent from the frequency for about 10–15min." Loss of communication in any form or duration is always a hazardous situation, but it is even more so after the 9/11 events.
What is causing all these problems? Like many safetyrelated occurrences, the answer is not simple, as there are a large number of factors that have played a role in the chain of events leading to air-ground communication problems. However, a number of factors really showed to be significant contributors to the problem. First, similar call signs on the same frequency was by far the most frequently cited factor. In such cases, pilots picked up an instruction intended for another aircraft that had a similar call sign. For the controller, it is not easy to identify this error, as the transmission may be blocked when two aircraft respond to the instruction. There were even a few cases in which four aircraft responded to the same instruction. The use of similar call signs should be avoided as much as possible. When this is inevitable, the following should be considered to mitigate the problem: pilots should use full calls signs (no clipping) in their readbacks; when there are similar call signs on the frequency, controllers should inform the pilots about it; pilots should actively monitor at critical flight stages using their headsets (instead of flight deck speakers). In Europe, the problem of similar call signs is being addressed by EUROCONTROL. Another important factor is related to frequency changes. In a large number of air-ground communication incidents analyzed, pilots forgot to change the frequency as instructed, or changed to the wrong frequency. Pilots should always check the selected frequency whenever the radio has gone unnaturally quiet in a busy sector. The NLR study identified many more factors, such as the use of non-standard phraseology (by controllers), radio interference, frequency congestion, and blocked transmissions. The vast majority of the factors identified are not new. Many of them have been there since controllers on the ground started to communicate with pilots using a radio.
In the future, some of the air-ground communication problems could be eliminated by the introduction of data link, for instance. However, such a system (and others) cannot eliminate all of our communication problems.
References used for this article:
Gerard van Es, Air-ground Communication Safety Study: An analysis of pilot-controller occurrences, EUROCONTROL/NLR, 2004 (www.eurocontrol.int/safety/gallery/content/public/library/com_report_1.0.pdf).
Gerard van Es et al., Air-Ground Communication Safety Study: Causes and Recommendations, EUROCONTROL/NLR, 2005 (www.eurocontrol.int/safety/gallery/content/public/library/AGC%20safety%20study%20causes_recommendations.pdf).
On December 20, 2005, an MU-2B-36 aircraft was taking off from runway 15 at Terrace, B.C., on a courier flight to Vancouver, B.C., with two pilots on board. The aircraft crashed in a heavily wooded area approximately 500 m east, abeam of the south end of Runway 15; about 300 m beyond the airport perimeter. A post-crash fire occurred. The aircraft was destroyed and the two pilots were fatally injured. The accident happened at 18:35 Pacific Standard Time (PST), in dark conditions. The investigation into this occurrence is ongoing (TSB file A05P0298).
To date, the investigation has revealed that the left engine (Honeywell TPE331-6-252M) failed as a result of the combustion case assembly (plenum) rupturing. This engine had accumulated 4 742 hr since the last continuous airworthiness maintenance (CAM) inspection. Investigation of the wreckage also revealed that the left engine was not delivering power and its associated propeller was not feathered at the time of impact. The flaps were also found at 20°, in the maximum deflection position. Tree damage revealed the aircraft had descended into the trees laterally, at a nose down angle of approximately 23°.
The following make up the checklist actions prescribed in the MU-2B pilot operating manual (POM) for an engine failure:
- Dead (failed) engine condition lever-EMERG STOP (to feather the propeller and shut off fuel at the fuel control)
- Dead (failed) engine power lever-TAKEOFF (to assist full feathering of the propeller)
- Landing gear switch-UP
- Flap switch-UP (after reaching a safe altitude and airspeed)
- Airspeed-BEST RATE OF CLIMB (150 kt calibrated airspeed [CAS])
- Trim ailerons-SET (to ensure no spoiler extension and loss of lift)
- Power (operating engine)-MAXIMUM CONTINUOUS POWER
The POM for the MU-2B permits takeoff using either flap 5 or 20. The advantage of using flap 20 for takeoff is that the aircraft will become airborne sooner; however, because of the greater drag caused by the higher flap setting, the aircraft's climb performance will be reduced.
If one engine fails after takeoff, the resulting loss of climb performance caused by the extended flaps would result in the aircraft not being able to achieve the climb gradient requirements specified for a given departure runway. The increased drag caused by an un-feathered propeller would further reduce performance. According to the POM, the combination of the loss of engine power, the extended flaps and the un-feathered propeller would result in the aircraft not being able to maintain altitude.
The MU-2B aircraft is a high-performance twin turboprop aircraft. About 400 MU-2 aircraft are active worldwide, including 309 in the United States and 16 in Canada. A number of them have crashed following engine failures during takeoff or immediately after becoming airborne. In situations in which an engine fails at a critical stage of the takeoff, the crew must take rapid and positive action to reduce the drag on the aircraft in order to maintain a positive rate of climb. Unless appropriate action is taken, there is a risk of loss of aircraft and related fatalities, such as were observed in this accident.
Based on the circumstances of this occurrence, Transport Canada may wish to remind MU-2B and other twin-engine operators of the importance of ensuring the required checklist actions are carried out immediately after recognizing an engine has failed on takeoff.
Computers in Aviation: Friend or Foe?
by Michael Oxner. Mr. Oxner is a terminal/enroute controller in Moncton, N.B., with 15 years of experience. He is a freelance aviation safety correspondent for http://www.aviation.ca/.
In days gone by, aviation was about stick and rudder; pilot skills were paramount in handling an airplane. These days, things are getting more complicated. Aircraft systems are becoming increasingly automated; flight information, such as flight status and weather conditions, is more readily available; and aircraft navigation systems are changing, allowing more flexible routes of flight, and less dependence on the ability of a pilot to fly a particular course from a ground-based navigation aid (NAVAID).
Computers make all of this possible; they receive information via data link rather than requiring a pilot to communicate by voice with dispatchers; they display the status of aircraft systems and position in more logical ways; and they do complex calculations for aircraft navigation, including automated guidance along programmed courses.
With all these advances in computer technology entering the cockpit, it's no wonder that sometimes the computers get the best of us. Each of us has, at some point or another, been in the position of being "behind the curve" with a computer of some kind. Whether it comes down to programming the clock on the VCR, playing a game on a computer, or dealing with a high-tech piece of hardware, we've all discovered that computers do exactly what they're told to do-even if we make a mistake in telling them what we want them to do.
There are few areas, however, where simple mistakes, such as transposing a digit, can result in serious consequences. Aircraft navigation is one of those places where anger can lurk in unexpected places. Sometimes it's an inadvertent error; sometimes it's getting carried away with the navigation equipment's capabilities; and other times it's a misunderstanding of the system and its effect. Here are a few examples of when things can go awry, and the reasons may be obvious, or they may be fairly subtle.
As a controller, I have witnessed a few of the subtleties of such errors. Once, a pilot had asked for direct BIMKU, the intermediate approach fix (IF) for an approach at an airport only 30 NM away. It should have amounted to a left turn of approximately 10°; however, the aircraft's track on radar appeared to change 110° to the left. When queried, the pilot told me he had inadvertently selected BIMTU from the database, a fix associated with another airport, about 100 NM north of his intended destination. If another aircraft had been on a parallel vector on his left side, this could have been very interesting, to say the least.
A similar error can be made when entering geographical coordinates. Accidentally entering 45°05'32" for latitude instead of 45°50'32" is a whopping error of 45 NM- all because two digits were transposed. Similarly, close placement of keys on a keypad can result in accidental selection of a nearby key-perhaps entering 48° instead of 45° in the previous example, which would have been even worse. One method of crosschecking such an entry for error is to compare the geographical coordinate to the desired entry backwards, helping to take the complacency factor out of data entry. It may take a little time, but it may also be well worth the investment.
Other errors that can occur can also be derived from complacency. Trusting the navigation system to get you where you want to go can be a mistake. Quite frequently, pilots ask for routings through restricted airspaces simply because a direct routing, made possible by GPS and other systems, is much easier to enter into a system. Looking at charts and picking out points takes time, and the practice also tends to take an aircraft off an optimal direct routing. However, a look at the charts during the flight planning stage may reveal reasons why a direct route is simply not acceptable to pilots or controllers.
Sometimes, pilots may make unintentional entries into navigation systems. While perusing a database for approaches, a pilot may inadvertently activate an approach and make a turn that ATC does not expect. Even a slight turn may compromise separation with surrounding aircraft, especially in a terminal environment where controllers apply minimum separation to use airspace as efficiently as possible.
Also, restricted airspaces may come into play during the transition from the en-route phase of flight to the approach phase. Saint John, N.B., for example, is located very close to the Gagetown, N.B., restricted area (CYR724), an area of live firing. Many pilots of varying experience have asked for clearances allowing navigation directly to fixes associated with an approach, only to have ATC deny the clearance. The reason is that many pilots tend to rely on the navigation gear to take them where they want to go, but forget about the possibility of obstacles or restricted areas between where they are at the time and where the desired fix is. The approach plates may have too narrow a focus to show the proximity of the restricted airspace, leading a pilot to believe there is no reason not to fly to a particular fix.
Another common error is when a pilot asks for clearance to an IF for an approach. If a turn of more than 90° is required for the aircraft to turn onto the final approach course, a pilot will sometimes program the autopilot to project a waypoint beside the IF, in effect making a base leg for the autopilot to fly. Some pilots doing this don't ask for approval for such a manoeuvre, and navigate to a point that ATC is not expecting, which may affect other traffic. Also, if the approach plate does not provide for such a manoeuvre, as an RNAV approach may, how does the pilot know what altitude is safe that far away from the final approach course?
Yes, computers can be our friends; they can offload a lot of work from a flight crew, especially those menial and repetitive calculations, but there are many pitfalls that can turn into big issues without proper care and attention. Familiarity with how a system operates, and what erroneous keystrokes may do, can literally save lives. Take care in the skies, and watch the computers carefully. They do what they're told to do, even if we don't realize what we're telling them to do.
While in cruise at FL 300 after departing Calgary, Alta., this Boeing 727 sustained extensive hail damage after an encounter with a severe thunderstorm. In addition to the damage shown, wing leading edges, engine inlets and landing lights lenses were also damaged. The aircraft returned to Calgary for an uneventful landing and was later repaired.
- Date modified: