Flight Operations

Instrument Cross-Check
by John Lorenz. This article is an authorized reprint from the January–February 2005 issue of Southwest Aviator magazine. For more articles, visit their online site at http://www.swaviator.com/.

Our IFR training does a good job of teaching the instrument scan for normal flying, as well as the more demanding partial-panel scan. However, most IFR training is seriously deficient when it comes to the important transition step between the two: the instrument cross-check technique that allows a pilot to recognize an instrument failure and thus prompts the change from normal to partial-panel flight.

The cross-check concept is taught-although its importance and application are not always made clear-during ground school, where we learn it as one of the three official "fundamentals" of instrument flying; the other two being instrument interpretation and aircraft control. We are also tested on knowledge of the system of primary vs. supporting instruments for various flight configurations. The system makes sense even though it is non-intuitive, but the important connection between this double-reverse/inverted system and its application as an instrument cross-check is rarely emphasized-and how many of us have actually been taught to regularly cross-check our instruments where it counts, in flight?

In fact, we tend to fly merrily along under the hood or in the clag using the primary instruments without cross-checking, i.e. backing them up. In part, this is because of how we’re taught: normal instrument flight runs smoothly enough without an instrument cross-check, so instructors can’t tell whether or not students are backing up the primary instruments, and therefore, they tend to gloss over it. Also, cross-checking is added work in what is already a task-saturated environment, so it tends to get dropped, usually without consequences. Yet, the instrument cross-check is an important backup measure that prevents a spatial-disorientation/unusual-attitude disaster by increasing the chance of early recognition of a failed instrument. Its importance only becomes apparent when an instrument actually fails.

The failures that an instrument cross-check is designed to detect cannot be demonstrated in flight. Simulators and computer training devices offer about the only opportunity to realistically train for gradual and/or unexpected instrument failures. Puckering liability issues dictate against installing a valve that can block the vacuum lines to simulate vacuum failure, and usually there are no switches to surreptitiously flick to disable an electric instrument. Yet, the importance of mastering the transition is apparent in several studies that have shown that: 1) it takes a significant amount of time, measured in minutes, for pilots just to recognize an instrument failure, and 2) this is plenty of time to get into real trouble. Coping with a failed instrument by using a partial-panel scan is an entirely different problem from recognizing the failure: the same pilots flew well enough in partial-panel mode when the instrument failure was known, suggesting that it is detection of the failure that is confusing, and that training for it is difficult, deficient, or both.

The flight instruments can be divided by whether they show roll, yaw, and/or pitch information, and theoretically you should cross-check flight indications in all three axes. However, roll and yaw in flight almost always occur together, and so, they can be lumped for simplicity. In order to cross-check roll/yaw indications, compare the attitude indicator/directional gyro (vacuum driven) with the turn coordinator (electrical). The imprecise magnetic compass can also be of some use in that if it is relatively stable, it indicates that the airplane is not turning, even if one of the other instruments shows it is.

Cross-check for pitch between: 1) the attitude indicator (vacuum), 2) the altimeter, airspeed and vertical speed indicators (pitot-static instruments), and 3) the power settings. Beware of the vertical speed indicator: it can wrap around far enough to give an erroneous, and therefore, confusing climb indication at high descent rates, and its indications lag significantly behind the actual conditions when pulling out of a steep dive.

One of the few places where the mechanics of an in-flight instrument cross-check have been described was written by Michael Church in Private Pilot magazine. Church suggests that turns, set up as a bank with the attitude indicator, should be backed up by checking to see that the turn coordinator agrees that the aircraft is actually turning, and in the desired direction. Simple enough so far: we do this anyway to establish the turn rate after establishing the bank. The less common flip side of the coin is that when the attitude indicator shows an unwanted turn, the turn coordinator should be checked to see that it corroborates the turn before trying to level the wings and coming back to a heading. Factor the heading indicator into these scenarios carefully, since both it and the attitude indicator are vacuum-driven, and could both be lying if the vacuum system is shot: cross-check to the vacuum gauge. If there is disagreement between instruments, take the time to figure out which one(s) are lying before making drastic moves.

Likewise, if the attitude indicator shows an unwanted descent, double-check with the airspeed indicator, vertical speed indicator, and/or altimeter before hauling back on the yoke. If you want to climb or descend, set it up with power and the attitude indicator, and then make sure the airplane is doing what you’ve told it to do by cross-checking to the same instruments.

Usually an instructor waves a heavy paw across the panel and slaps a cover on an instrument to simulate failure: there might as well be a red flashing sign: "Go To Partial-Panel, NOW!" It is much more difficult to detect the subtle and confusing indications of a real instrument failure, but it is imperative to do so because the chance to demonstrate dazzling partial-panel skill never occurs if the pilot does not first recognize the opportunity.


Release of Seat Belts from the Seat Anchoring Point
An Aviation Safety Advisory from the Transportation Safety Board of Canada (TSB)

On July 25, 2006, a de Havilland DHC-8-100 departed St. Theresa Point, Man. (CYST), for Winnipeg,Man.(CYWG), with a crew of three and fourteen passengers. While en route at FL 200, the crew noticed a thunderstorm ahead of them, but well below their flight path. The crew turned on the seat belt sign and the flight attendant ensured that all passengers were seated with their seat belts fastened. As the aircraft approached the cloud, the crew noticed it was developing vertically rapidly; they turned westward to skirt around the edge of the disturbance, but encountered an area of turbulence. One large bump was felt that dropped the aircraft and caused loose articles in the cockpit and cabin area to hit the ceiling. Two of the passenger seat belts released, throwing the passengers from their seats. One of the passengers who was released was holding a five-month-old infant. Both hit their heads on the ceiling, causing minor bumps. The other passenger who was released was visibly shaken and could not move. The passenger was later assessed as having minor injuries. Several other passengers received minor flail injuries. The passengers whose seat belts released were moved to other seats, and their injuries were assessed. After landing in Winnipeg, all passengers were taken to hospital, treated, and later released.

The two seats belts that failed were from the aisle seat locations. The seat belts, part number 502745-E-2847, model number 502751, are manufactured by AmSafe Inc. of Phoenix, Ariz. The seat belts are snapped onto the seat attachment point with a hook, which incorporates a spring keeper for quick installation and removal. The seat, ID number 8S0151-1/-2, is manufactured by PTCAerospace (now owned by B/E Aerospace). The seat incorporates a U-shaped attachment fitting bolted to the seat structure to accommodate the seat belt.

The two seat belts that failed had flipped around the U-shaped attachment fitting, and became lodged under a plastic trim molding on the side of the seat, adjacent to the aisle. A direct pull on the belt bent the spring keeper to the side, allowing the belts to become detached, even though the hook remained undamaged.

Figure 1: Seat belt hook snapped

Figure 1: Seat belt hook snapped
onto U-shaped fitting-pull is on hook

Figure 2: Hook flipped under trim molding

Figure 2: Hook flipped under trim molding
-pull is on spring keeper

Figure 3: Bent spring keeper

Figure 3: Bent spring keeper

Figure 4: Seat belt identification

Figure 4: Seat belt identification

The seat belt is manufactured with a hole through the spring keeper to accommodate a cotter pin to lock the keeper in place. The locking provision was intended to prevent the unwanted removal of the seat belts. There is no Technical Standard Order (TSO) requirement by either the seat or seat belt manufacturer to have the cotter pin installed; the installation of the cotter pin is at the discretion of the operator. Misaligned seat belt clasps, without the cotter pin installed, take less of a pull to detach the seat belt from the seat attachment fitting. With the cotter pin installed, the misaligned belt has a better chance of aligning itself before a detachment occurs. These particular seat belts had the optional cotter pin installed.

Similar types of seat belt failures produced by the same seat belt manufacturer, but without a cotter pin installed in the spring keeper, were reported in two separate accidents referenced in Special Airworthiness Information Bulletin(SAIB) NM-04-37, issued on December22,2003, by the Federal Aviation Administration (FAA). In NM-04-37, the belts became detached from a Clevis-style attachment fitting, referred to as a "D-ring." Transport Canada issued Service Difficulty Advisory (SDA) AV-2004-02 on February12,2004, referencing the SAIB. BothSAIBNM-04-37 and SDA AV-2004-02 referenced over 20aircraft manufacturers with many more aircraft model types having the potential for a similar occurrence.

Although SAIB NM-04-37 did not detail injuries sustained in the release of the seated occupants, both the FAA and the TSB are in agreement that the potential for serious or life-threatening injuries exists if the belts were to release during an aircraft accident, in-flight turbulence, or a hard landing. This occurrence demonstrated the possible alignment/interference problem associated with this particular seat and seat belt arrangement; however, the possibility of similar alignment/interference issues could exist for any seat using this quick-release-style seat belt.

Therefore, Transport Canada may wish to advise other commercial operators of the circumstances of this occurrence. As well, regulators and manufacturers may wish to consider the requirement for a special inspection to ensure that alignment or interference issues with this type of seat belt cannot occur, and that the optional cotter pin is installed as a permanent fixture.


Be Prepared: What If an Emergency Happened to You? Part I
by Karen Smith, Inspector, Cabin Safety Standards, Civil Aviation, Transport Canada

Emergency! Emergency!

Those are the words you never want to hear when you are sitting in your passenger seat. Would you be able to switch to emergency mode in seconds? Flight attendants are trained to react quickly to emergency situations, but it is the preparation before an emergency that helps to ensure a successful outcome. This preparation comes in many forms, from the safety briefing to passengers prior to takeoff, to checking emergency equipment on the aircraft before the flight, to annual training. Flight attendants must balance the use of procedures and equipment on board with the unpredictable reactions from passengers-a daunting task under normal circumstances, much less amid the potential chaos of an evacuation. How do flight attendants-these masters of planning and crowd control-achieve this? By being prepared.

A good briefing is worth a thousand words

Good planning for a flight starts with the mandatory crew briefing between pilots and flight attendants. It is an opportunity to ask questions and get a clear picture of the flight ahead. Crew members should take the time to conduct a complete briefing, defining roles and responsibilities, discussing en-route weather, passenger loads and special needs, emergency equipment, safety and emergency procedures and any additional information necessary for the flight. Good communication, as we all know, is essential to an effective and successful flight, but is even more crucial in the event of an evacuation.

The passenger briefing prior to takeoff is an integral part of the preparation of a flight. Regulations ensure that passengers have received a briefing in both official languages at the beginning of the flight, and that all the pertinent information necessary to "survive a crash" is in that briefing and the safety features card found in front of the passengers’ seat. All too often, many passengers do not pay sufficient, if any, attention to the safety briefing. Studies show that ill-prepared passengers can be a hindrance in an evacuation. Flight attendants are constantly seeking innovative ways to engage passengers’ attention for this vital briefing, as they understand the importance of the information that is being transmitted. Flight attendants also attend to passengers with special needs who may require individual briefings. Every passenger must receive information on the location of exits, the safety features cards and emergency lighting, the fastening of seatbelts, and if applicable, the use and location of oxygen masks or life preservers. The next time you fly, listen to the briefing, look at the safety features card in front of you, take responsibility for your own safety and be prepared.

Batten down the hatches

Once the passengers are briefed, the flight attendant(s) will ensure the cabin is prepared for takeoff. This is achieved by visually inspecting the cabin area to verify that all carry-on baggage is safely stowed in overhead bins or under seats, babies are in car seats or lap-held in a safe manner, seatbelts are fastened snugly across passengers’ hips, seat backs are in the upright position, cabin doors are armed, and galley equipment and compartments are locked. Bags and articles, if not properly stowed, maybecome projectiles and obstructions that could injure or hinder passengers and crew. A properly-secured cabin can be evacuated more efficiently than an unsecured cabin. The next time you fly, ensure that you have done your part to help secure the cabin prior to takeoff by following instructions and stowing your items. Be prepared.

No, I’m not ignoring you

When the cabin is prepared for takeoff, the flight attendant(s) will advise the captain and take their assigned seat and, as they do for every takeoff and landing, they will conduct a silent review. Have you ever wondered what flight attendants are thinking about while seated on a jumpseat? The silent review is a mental checklist. It is a review of exit locations and operation, evacuation routes out of the aircraft, commands to be used to guide passengers, and identification of passengers who may be selected to assist with an evacuation. Although it might appear that the flight attendant is ignoring you, this technique helps to keep procedures in order for a flight attendant who may fly on numerous aircraft types, where equipment may be different, and the layout of the cabin and functioning of exits or procedures may not be the same. As a passenger, you too can do a mental review, know where your nearest exit is, count the rows to that exit and be familiar with how it operates. Be prepared.

Brace yourself: prepared or unprepared evacuation

An emergency can happen upon takeoff or landing. With some emergencies, the crew has prior notice of a problem and time to prepare the passengers. With other situations, there is no prior warning, no time to prepare, flight attendants must use the procedures for which they are trained to control, direct and assist passengers to evacuate. Would you be able to switch to emergency mode in seconds...?

Join us in the next issue of the Aviation Safety Letter, when we look at the dynamics of an aircraft evacuation from the cabin safety perspective.

Cross-Country Flying in Short-Legged Aircraft...Planning Helps
by Bob Merrick. Bob is a System Safety alumni who promotes aviation safety in all he does. He writes regularly for COPA Flight.

Although it’s hard to find accurate statistics, it seems that the practice of using light aircraft for long voyages is increasing. Certainly, COPA Flight, the monthly paper published by the Canadian Owners and Pilots Association (COPA) for its 17 000 general aviation readers, often carries accounts of odysseys undertaken by their members; odysseys that take those members far from their starting point, often over some forbidding terrain, or through areas where the climate can be totally unaffected by global warming.

The common thread in such articles is the pre-flight planning required. No, not the kind of planning that says, "we’ll fly this heading for a while until we reach East Porcupine Quill, then crank over to about 285°M, which will take us to Grand Central Nowhere." That sort of planning is vital, no doubt about it, and it’s particularly vital for the day or days of the excursion, but it’s relatively short-range.

Most of those pilots planning extended flights in short-legged aircraft start their planning well before the preferred launch date. Some start by reviewing the pilot’s qualifications. How recent is their experience? Is it necessary to apply a new coat of polish to skills (and knowledge) that have become somewhat atrophied since the previous flying season? Local flying schools and their instructors are generally quite happy to remove any rust that might have formed on dormant skills.

Others start with the aircraft. Although modern aircraft are far more reliable than their long-ago ancestors, their engines can still go into auto-rough when flown off the beaten path. Where is your aircraft in its maintenance cycle? "It’s good until we get back," you say? Perhaps a check before starting out might not be a bad idea.

Mechanical things have this way of having dizzy spells from time to time. A consultation with your favourite aircraft maintenance engineer (AME) can help uncover incipient problems that, in the general cussedness of things, occur at the worst possible time, in the worst possible place.

Most readers know that we are now getting to the point where there are rules for everything. Just to keep life interesting, those rules keep changing, and the changes are promulgated in various dated publications. Be they electronic, be they paper, or be they chiselled into stone tablets, they are all dated, and woe betides those who take their information from one or two issues ago. Current publications, in whatever form you choose to carry them, are a must. Don’t leave home without them, as you might not get back.

Many people will throw in a hand-held GPS, thinking that they will be right on track, all the time. And so they will, at least until the batteries die. Even if the batteries don’t die, there is always the risk of doing as one pilot did about a decade ago. He was faithfully following his GPS right up to the point where he flew smack dab into a mountain that had been there, right in the middle of the track, long before GPS. Current charts are essential.

Should your route take you into the United States, a passport is a necessity. Since January 23, 2007, all people-pilots and passengers-arriving in the U.S. by air must have a valid passport. If your passport is likely to expire during your journey, renew it now. As this is written (February 2007), there is about a 40-day waiting period for a new passport, so don’t let this requirement slide. It could spoil your entire holiday.

There are other things that could spoil your holiday; things that you really can’t control. A few paragraphs back, we were extolling the virtues of modern aircraft, which seldom break down in mid-flight. Thus, we don’t have to worry about that, do we? Sadly, the answer is: "yes." Modern aircraft can, and do, get tired of flying, and head for the nearest patch of ground.

One of the major reasons you sprang for that pilot refresher course was so that you could handle just such an eventuality. After using your newly-enhanced skills to put the aircraft on the ground in one piece (more or less), the question is: "now what?"

The answer depends on the severity of the forced landing. Are you and your passengers prepared to spend a night in the bush, or is everyone attired in a tasteful collection of shorts, T-shirts and sandals? Although David Suzuki might differ, you cannot, for a good many years, rely on global warming to keep you cozy and comfortable during an unplanned overnight stay in the Canadian wilderness. Your pre-odyssey flight planning should encompass such details as care and feeding of your emergency locator transmitter (ELT) and survival gear during impromptu camp-outs.

What else might you think about? Of course, summoning help. How do you do that? With your ELT, that’s how. Turn it on and leave it on. Until 2009, COSPAS-SARSAT satellites will hear the plaintive wails, forward them to the search and rescue (SAR) network, and erelong, a SAR aircraft will arrive. After2009, such satellites will no longer monitor the aviation voice distress frequencies of 121.5/243.0 MHz. Cell or satellite phonescan supplement the ELT for reaching out and touching someone.

However, it’s not an "instant SAR kit." It can take 90 min or so for the system to localize your position, and, depending on weather, your location and other factors, it can take several hours or more for the SAR aircraft to arrive at the scene.

Such planning is necessary for traversing remote areas. Are you likely to need such plans? Well, no, but if such incidents are not considered in the planning stages, you’ll have to deal with them when things go wrong. That is the wrong time to wish that you had brought a jacket, some matches and several quarts of bug repellent.

The continual improvement in aircraft, aero engines, electronics and communication gear has done much to reduce risk in aviation, but it hasn’t eliminated it. Thorough pre-flight planning can reduce the risk even further.

And what is the reward for all that work? Well, according to the enthusiastic articles in COPA Flight, pilots and their passengers get to view magnificent vistas seldom seen by lesser mortals who are forced to fly with "Air Megaseat" some seven miles above one of the most scenic lands on earth. Not for them the thrill of seeing the mountains, the prairies, the lakes, with the shifting, dancing colours, or to experience the joys of flight as seen from a light aircraft. A light-aircraft odyssey across a wonderful country is something few people get to do. It’sa privilege, and like all privileges, it must be earned. Your thorough pre-flight planning is part of the price you must pay for such a remarkable experience. But, it’sworthit. Have a wonderful trip!

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