- ISSUE 3/2008
- Copyright and Credits
- Guest Editorial
- To the Letter
- Flight Operations
- Maintenance and Certification
- Recently Released TSB Reports
- Accident Synopses
- Regulations and You
- The Civil Aviation Medical Examiner and You
- Debrief: The Luck Meter—Don't Leave Home Without It!
- Don't Let It Get This Far! Runway Incursions Are Real! (poster)
- Full HTML Version
- PDF Version
- See, Hear, Comply and Avoid-Maintaining Separation at Uncontrolled Aerodromes
- Back to Basics: Weight and Balance
A search of the aviation investigation reports published by the Transportation Safety Board of Canada (TSB) indicates that there have been several instances of in-flight collision and risk of collision in Canada in recent years. The consequence of aircraft occupying the same location in time and space rarely yields results that are less than tragic. Many in the aviation community may harbour vivid recollections of close encounters with other aircraft in otherwise unremarkable or outright benign circumstances.
The range of potential scenarios is extensive and, on occasion, the occurrence venue is airspace in close proximity to uncontrolled aerodromes. There are recorded instances of aircraft departing from or arriving at uncontrolled aerodromes under VFR, or under IFR in visual meteorological conditions (VMC), and unexpectedly finding themselves in close quarters with other traffic. Aircraft in the VFR traffic circuit have been known to conflict with one another even when operating with the benefit of air traffic services (ATS). Fixed-wing and rotary-wing traffic operating in relatively remote settings have historically found themselves in close quarters, both in the field and at nearby community aerodromes typically served by aerodrome traffic frequency(ATF) communication procedures. Examples of periods of heightened activity in terms of traffic volume would include major forest fire fighting efforts and the initial stages of natural resource development projects.
The predominant failing that arises in the vast majority of in-flight collisions is the failure to see and be seen as well as hear and be heard(i.e. avoid). So, what can be done to alleviate or mitigate the risk of collision? Does the answer lie in maintaining vigilance in our visual scanning, being alert to rapid and unacceptable loss of separation, and reacting well in advance of a deteriorating traffic situation; or in adherence to established regulations and procedures and communicating with other aircraft that we share airspace with? The answer likely rests in a combination of each of these defences.
In general, pilots will agree that visually detecting other aircraft can sometimes be very difficult. Most cockpits present challenges to effective visual scanning and the ability to search for and detect other aircraft. Impediments to the process include vision-obstructing struts, posts, doorframes, glareshields, and perhaps a fellow pilot or passenger. In addition, dirty, fogged, scratched andbug-splattered windshields, as well as flight in reduced visibility due to weather, or other obscuring phenomena such as smoke, can further complicate the task, as can vibration, fatigue and workload. Increased attention to cockpit automation and instrumentation can take away from time spent scanning the surrounding airspace for threats to safe separation. Accessibility of sunglasses to combat glare and choice of headgear are also part of the equation. A peaked ball cap may shade the eyes, but it might also restrict peripheral vision in the vertical plane; a factor of particular relevance when operating aircraft that, by virtue of cockpit design, would otherwise provide for enhanced peripheral vision in the vertical axis. Even detection of aircraft in a clear sky can be hindered by what is known as "empty-field myopia." Shari Stamford Krause,PhD1, herself a pilot, describes this as a condition whereby, in the absence of a visual stimulus (for example, empty space), the muscles in the eye relax, preventing the eye from focusing. This creates a problem for a pilot who is attempting to scan for traffic in a clear, featureless sky. Because the eye cannot focus on empty space, it remains in a state of unfocused, or blurred,vision.
Maintaining vigilance in our visual scanning is critical to the see and be seen (or see and avoid) concept.
In an unrelated but pertinent study conducted by the Lincoln Laboratory2 during traffic alert and collision avoidance system (TCAS) flight testing, data showed that a pilot alerted to the presence of other aircraft visually acquired the other aircraft in 57 of 66cases; the median range of visual acquisition was 1.7NM. In cases where the pilot was not alerted to the presence of the other aircraft, visual acquisition of the other aircraft was achieved in only36of64encounters. In the successful encounters, the median acquisition range dropped to 0.99NM. These studies showed that verbal guidance as to where to look increased the acquisition probability for the pilots, and found that a pilot who had been alerted to the presence of another aircraft was eight times more likely to see the aircraft than the pilot who had not been alerted. The test aircraft involved in the study were light twinengine aeroplanes. Radio advisory calls, TCAS, if fitted, and strobe/landing lights are all means of communicating an aircraft’s position to other traffic.
As pilots, we have a responsibility to read and know the Canadian Aviation Regulations(CARs). Procedures in place for effectively maintaining separation around uncontrolled aerodromes can be found in the Transport Canada Aeronautical Information Manual(TCAIM). This publication is available in print and on-line at: www.tc.gc.ca/eng/civilaviation/publications/tp14371-menu-3092.htm. The published procedures are, in fact, regulations and adherence is required. Traffic that complies with the prescribed procedures will have the expectation that other aircraft are acting in a similar manner. It should be noted that the Aeronautics Act defines an aerodrome as:
No person shall conduct or attempt to conduct a take-off or landing in an aircraft until there is no apparent risk of collision with any aircraft, person, vessel, vehicle or structure in the take-off or landing path.
Mandatory frequency(MF) vs. aerodrome traffic frequency(ATF)...What’s the difference?
The following extract is taken from the RAC section of the TC AIM and is summarized for easy reference in the General section of the Canada Flight Supplement(CFS) under the Communications (COMM) sub-section.
Note: Although lengthy in content, it is considered to be in the interests of aviation safety to reproduce the pertinent references.
4.5.4 Mandatory Frequency
Transport Canada has designated[an MF] for use at selected uncontrolled aerodromes, or aerodromes that are uncontrolled between certain hours. Aircraft operating within the area in which the MF is applicable (MF area), on the ground or in the air, shall be equipped with a functioning radio capable of maintaining two-way communication. Reporting procedures shall be followed, as specified in CARs602.97 to 602.103 inclusive.
An MF area will be established at an aerodrome if the traffic volume and mix of aircraft traffic at that aerodrome is such that there would be a safety benefit derived from implementing MF procedures. There may or may not be a ground station in operation at the aerodrome for which the MF area has been established. When a ground station is in operation, for example, an FSS[flightservicestation], an RCO[remote communications outlet] through which RAAS[remote aerodrome advisory service] is provided, a CARS[community aerodrome radio station], or an approach UNICOM, then all aircraft reports that are required for operating within, and prior to entering an MF area, shall be directed to the ground station. However, when the ground station is not in operation, then all aircraft reports that are required for operating within and prior to entering an MF area shall be broadcast. The MF will normally be the frequency of the ground station which provides the air traffic advisory services for the aerodrome....
4.5.5 Aerodrome Traffic Frequency
An[ATF] is normally designated for active uncontrolled aerodromes that do not meet the criteria listed in RAC4.5.4 for an MF. The ATF is established to ensure that all radioequipped aircraft operating on the ground or within the area are listening on a common frequency and following common reporting procedures. The ATF will normally be the frequency of the UNICOM where one exists or 123.2 MHz where a UNICOM does not exist....The designation of an ATF is not limited to aerodromes only. An ATF may also be designated for use in certain areas other than the area immediately surrounding an aerodrome, where VFR traffic activity is high, and there is a safety benefit to ensuring that all traffic monitor the same frequency. For example, an ATF area could be established along a frequently flown corridor between two uncontrolled aerodromes....
4.5.7VFR Communication Procedures at Uncontrolled Aerodromes with MF and ATF Areas
- Radio-equipped Aircraft: The following reporting procedures shall be followed by the pilot-in-command of radioequipped aircraft at uncontrolled aerodromes within an MF area and should also be followed by the pilot-in-command at aerodromes with an ATF:
- Listening Watch and Local Flying[CAR602.97(2)] Maintain a listening watch on the mandatory frequency specified for use in the MF area. This should apply to ATF areas as well.
- Before Entering Manoeuvring Area (CAR602.99) Report the pilot-in-command’s intentions before entering the manoeuvring area.
- Departure (CAR602.100)
- Before moving onto the take-off surface, report the pilot-in-command’s departure intentions on the MF or ATF frequency. If a delay is encountered, broadcast intentions and expected length of delay, then rebroadcast departure intentions prior to moving onto the take-off surface;
- Before takeoff, ascertain by radio on the MF or ATF frequency and by visual observation that there is no likelihood of collision with another aircraft or a vehicle during takeoff; and,
- After takeoff, report departing from the aerodrome traffic circuit, and maintain a listening watch on the MF or ATF frequency until clear of the area.
- Report before entering the MF area and, where circumstances permit, shall do so at least five minutes before entering the area, giving the aircraft’s position, altitude and estimated time of landing and the pilotin- command’s arrival procedure intentions;
- Report when joining the aerodrome traffic circuit, giving the aircraft’s position in the circuit;
- Report when on downwind leg, if applicable;
- Report when on final approach; and,
- Report when clear of the surface on which the aircraft has landed.
- Continuous Circuits (CAR602.102)
- Report when joining the downwind leg of the circuit;
- Report when on final approach; stating the pilotin- command’s intentions; and,
- Report when clear of the surface on which the aircraft has landed.
- Flying Through an MF Area (CAR602.103)
- Report before entering the MF or ATF area and, where circumstances permit, shall do so at least five minutes before entering the area, giving the aircraft’s position and altitude and the pilot-in-command’s intentions; and,
- Report when clear of the MF or ATF area.
NOTE: In the interest of minimizing possible conflict with local traffic and minimizing radio congestion on the MF or ATF, pilots of en-route VFR aircraft should avoid passing through MF or ATF areas.
- NORDO: NORDO[no radio] aircraft will only be included as traffic to other aircraft and ground traffic as follows:
- Arrival: from five minutes before the ETA[estimated time of arrival] until ten minutes after the ETA, and
- Departure: from just prior to the aircraft departing until ten minutes after the departure, or until the aircraft is observed/reported clear of the MF area.
Carrying and referring to updated charts and a current copy of the CFS will help to ensure that correct frequencies for flight in the vicinity of uncontrolled aerodromes are selected on the aircraft radio. Relying on memory to recall MFs and ATFs for specific uncontrolled aerodromes can be problematic, especially at times of increased workload, and in light of the fact that frequencies may be subject to change. Global positioning system (GPS) data cards can provide a great deal of information at the push of a button, but that information can be a contributing factor to disaster if it is not accurate, hence the need for a current data card.
In conclusion, it is perhaps realistic to note that operational and self-imposed pressures to meet timelines and objectives can sometimes influence and cloud our perception of the airspace environment around us and how we fit into it. Risk factors associated with flight in the vicinity of uncontrolled aerodromes can be greatly reduced with the application of acute visual and aural awareness combined with familiarity with, and adherence to, the established rules and procedures. Used in conjunction with timely position reports and the communication of intentions between aircraft, these defences build and reinforce situational awareness and, ultimately, serve to assist aircraft in their avoidance of one another.
- Shari Stamford Krause, PhD, Flight Safety Digest, May 1997.
- J.W. Andrews, "Modeling of Air-to-Air Visual Acquisition," The Lincoln Laboratory Journal, Volume2, Number3, 1989, p.478.
Back to Basics: Weight and Balance
This article is an authorized reprint from the November/December2001 issue of Southwest Aviator Magazine. This and many other excellent safety articles can be found on their Web site at http://www.swaviator.com/.
It’s confession time. Let’s see the hands of everyone who will not leave the ground without doing a proper weight and balance. About onein20? That’s about what I thought. Now, let’s see the hands of everyone who has ever seen another pilot perform a weight and balance before the flight. Let’s see. One out of 300. That’s about right. Now, let’s see the hands of all those who would be dead if someone put a gun to their head and said they were going to shoot them if they couldn’t show them the proper way to do a weight and balance. About four out of five of you should admit to that one.
While it may be covered under that ubiquitous[U.S. Federal Aviation Regulation(FAR)] concerning doing everything to make sure the flight can be conducted safely, it’s safe to conclude that weight and balance is one of the most overlooked aspects of flying. There are some who might pay more attention to it than others. I understand that pilots of V-Tail Doctor Killers had better pay attention. I’ve also read that pilots of 182s and Cherokee-Sixes don’t need to be as concerned. But let’s face it. You can load any airplane wrong and it will crash. Seems like the pilots of a 707 learned that in Miami,Fla., a few years ago.
If you get the feeling that your aircraft is near or above its weight and balance limits, you are probably right.
Shortly after Dr. Tim Williams became a partner in our Bellanca, he called me and said, "I’ve been doing a weight and balance on this plane, and it appears that if you have four people on board and full fuel, you’ll be beyond the aft[centre of gravity(CG)]. Is that right?" "Beats me," I told him, "I’ve never done one. What I do know is that I’ve had four big folks on board with full fuel and it flew." And it did. I’ve done it several times with no clue as to what the charts would show. I don’t think we were too far off, but I didn’t know for sure on the[CG]. Addition and subtraction are easy enough, so I was pretty sure on the weight, but balance? That’s another matter. The guy we bought the plane from told me it would be ok, and I believed him.
One of the problems with doing a weight and balance is that the things are so complicated. Moment and arm and datum. What is all this stuff? If somebody would just simplify the process. You say something like, "If Bubba is the pilot, and he weights250, and Charlie is in the right seat, and he weighs220, and if Martha and Myrtle are in the back seat, and they weigh375 together, and you have 100pounds of luggage, and you try to fly that bugger, you better make sure your will is current, because you’re about to use it." That language I can understand. It makes much more of an impact than all those charts and graphs and lines. With all the computer technology that’s out there, you’d think that at least the manufacturers of new airplanes would come up with an automated system. They could put an electronic scale in each seat. Same with the luggage. Fuel sensors detect how much fuel is on board and where. Everything is calculated by a computer, which plays "Lord, I’m Coming Home" if the airplane won’t fly. That should get people’s attention.
It’s probably a good thing that I took my check ride with old Earl Sharp in a Cessna 150. It’s good because Earl wasn’t too strict anyway, and it’s also good because there’s not a lot of[CG] questions you can ask about weight and balance on a150. Seems to me like he asked something about whether or not I had checked the weight, but at least the question about how much weight we could put in the back seat was moot, and he didn’t ask about luggage. Gratefully, he also didn’t ask me to do a weight and balance problem for him. If he had, I’d probably still be a student pilot.
Now don’t get me wrong. I have done a weight and balance. About a year and a half ago, Robin, John and I were going to Houston, Tex. Robin was kind of short on experience and confidence in the plane, so he invited along some company. Robin was flying, because he was paying for the gas, or rather one of his clients was. John was riding front seat to keep us all safe from Robin, and I was relegated to the back. Sitting there, I noticed the operations manual in the seat back in front of me, and since it had been a while since I had perused it in detail, I decided to do so. I came across the section on weight and balance, and decided to try to do one. Pulling out my trusty pocket calculator, I plugged in the numbers, only to find out that when we took off, we were 100 pounds over gross, and a couple of inches past the aft[CG], assuming I knew what I was doing, which might be questionable. I didn’t bother Robin with my newfound knowledge. It would have just depressed him.
That’s not to say that I’ve never had[CG] concerns. About a year ago, my daughter and two of her friends went on a "road trip" to Waco,Tex. On the way back, in the little town of Clifton,Tex., a little old lady on her way to church ran a stop sign and hit them. Nobody was hurt, but that car wasn’t driving home. Clifton is about six hours from Lubbock,Tex., so for someone to drive to get them would have been a long adventure. The obvious solution was for me to fly down.
Since it was a Sunday, I knew that the probability of fuel being available in a town like Clifton was iffy at best. Even if it hadn’t been a Sunday, it would have been iffy. Accordingly, I topped off every tank before I left. I climbed out on the left, burned the 15-gal.[auxiliary] tank for one hour, which should have almost burned it dry, and landed on the right.
There are a couple rules of flying etiquette that need to be mentioned here. Rule number one is that when daddy is the pilot, you always get to ride shotgun. Rule number two is that you never ask a big woman to do anything that would reveal that you noticed how big she is, at least not if you value your health.
There are times in life when you can’t win. You see, Susan is a big girl. She’s not fat. She’s just big. Put another 30pounds on her and she can play middle linebacker. I had this gut feeling that Susan should be up front with me, but she dutifully climbed in the back where any passenger who isn’t related to the pilot is supposed to be. Trying to justify taking off with her there, I reasoned that Lisa and Sara were about the same weight, and that hopefully I weighed about the same as Susan, or at least close. That should balance, I thought. The[auxiliary] tank, which sits under the rear seat, was empty. They hadn’t taken a lot of luggage with them. We should be ok.
Having flown the plane with weight in the back before, I was expecting the plane to fly differently. I had a little extra nose down trim cranked in. The pull on the yoke to make it fly would be a lot less. I was ready.
Liftoff was smooth and the plane flew normally. I had told myself that if anything at all didn’t feel right, I was setting it back down, but everything was fine. The climb was slow due to the load and the 90°F temperature, but otherwise normal. The fun began when I started to trim the nose down to level off. The trim tab, which is on the top of the cabin in a Bellanca, stopped turning after a couple of turns. My immediate thought was that the trim mechanism had jammed, but when I looked up at the ceiling, I noticed the problem was something quite different. The trim tab was at its full nose down stop. There was nothing wrong with the trim. I had just run out of it.
I pushed forward on the yoke, and the nose came down and stayed down. Everything was still under control, and the closer we got to home, the more normal the trim became.
I had flown the plane before with four big people on board, but never with two little people and two big people. My assumption that everything would be the same wasn’t true. Everything turned out ok, but it could have been a recipe for disaster.
So, have I started doing a weight and balance before every takeoff? Of course not. Most of the time, I’m the only person on board, and it hardly seems necessary. Even with two on board, I’m not sure I would learn a lot. But the next time I have four on board? Well, I might be more prone to dusting off that old book and seeing if I can figure out some of those graphs.
"Did you know?"
The arrival of civil aircraft flying VFR from the United States without search and rescue (SAR) being activated is a concern. Differences between Canada and the United States can lead pilots to believe their flight plans have been opened. These differences are highlighted in the article "Flight Planning Issues," published in Aviation Safety Letter(ASL)2/2007. One of the differences discussed in the article is that after filing a flight plan in the United States, you need to activate it with an American flight service station (AFSS). The article can be found on-line,at http://www.tc.gc.ca/eng/civilaviation/publications/tp185-2-07-operations-3675.htm...it’s worth reading!
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