Wednesday, 14 September 2016
The following is condensed from an article published in the Autumn edition of the GASCO Flight Safety Magazine.
Acknowledgements and thanks: GASCO/Gerry Humphreys
Loss of control is increasingly evident in fatal accidents in both GA and commercial operations, and the key to avoiding it is Angle of Attack Awareness.
For those wanting to learn to fly in as short a time as possible simulators are used to teach standard and emergency procedures, and to minimise costs. However, they do not recreate the effect of “G”, without which the trainee is missing out on experiencing instruction in an important skills area. Thus many trainees rarely get to fly a turn above 450 angle of bank, or a pitch of 200.
AoA is important in determining whether a wing flies or not, so understanding it is vital if we are to understand what is happening when we pilot an aircraft. LIFT and DRAG are directly related to SPEED and AoA, but whereas we seem to concentrate on speed, AoA is the more fundamental concept to be grasped; because STALL is related to AoA alone. A good Instructor will thus introduce the concept of AoA at an early stage of training.
Primary Elevator effect:
Stick back, AoA of wing increases, lift increases, aircraft climbs
Secondary Elevator effect:
Stick back, AoA of wing increases, drag increases, speed decreases
Speed .v. AoA relationship:
High speed, Low AoA; Low speed, High AoA
Primary Aileron effect:
Change in the LOCAL AoA, which alters Lift and Drag in their own Area. Wing rises,
Lift & Drag increase; Wing falls, Lift & Drag decrease
Secondary Aileron effect:
Yaw in the opposite direction to the input roll. In an established bank, an aircraft will first
slip then yaw in the same direction as the input roll, but at this stage the ailerons are actually
NEUTRAL. Any subsequent slip & yaw will be an effect of Angle of Bank & Stability,
not aileron control input
Keep the ball in the middle:
If not, the ailerons will be deflected, with one wing at a higher AoA than the other.
Approaching a critical overall AoA, the down-deflected aileron will stall first
Of limited value in the real world, as most fatal spins occur too close to the ground to enable
recovery. Better to train prevention by means of realistic stall training incorporating AoA
Feeling the Force:
Much steep-turn training is done at 450 AoB, but training at 600 AoB as well is beneficial
in two ways:
- It demonstrates that the increased lift needed demands an increased AoA:
Stick back further = more lift = more drag = more power required
- The pilot can experience what 2G feels like, and if on pulling the stick back you feel 2G,
you have enough lift to fly. You will not stall unless speed reduces, so given sufficient
terrain clearance and the application of correct technique, recovery is achievable. If you
don’t feel the force you need more speed or a lower AoA for the lift equation to work
Monday, 5 September 2016
John says: Sometimes the only way to learn an important lesson is to scare yourself just a little. We try to fill the experience bucket before the luck bucket gets to empty. Here are seven common ways to do it, and before you say it could never happen to you, remember that pilots don’t crash aeroplanes because they want to. That’s why we call them accidents.
1. Run low on fuel. So common, and yet fuel is one thing we have almost total control over. Poor planning combines with ‘get-home-itis’ until the pilot runs low on both fuel and options. Most of the time, the pilot lands before the engine quits, but usually not before a lasting impression is made.
Lesson: Be pessimistic in your calculations. Aim always to land with one hour of fuel in the tanks.
2. VFR into IMC/scud running. Similar causes, but whereas low fuel is pretty easy to monitor, there is no instrument to measure “low weather.” There are FARs to define legal VFR, but where’s the line between safe and legal? Pilots sometimes become overly optimistic, taking false comfort when the forecast says “it shouldn’t be this bad.” The only weather report that matters is what you see ahead. Ignore it and, you scare yourself by flying dangerously low or skimming in and out of cloud.
Lesson: Trust METARs, and the trends indicated in them, more than TAFs. Consider your flight as a series of “go a little further/stop going” decisions instead of a single “go/no go” option. If you have to go down or slow down more than once, it’s time to divert.
3. Close call in the traffic pattern. Most pilots can remember at least one close call, with one flying a standard pattern and another making up his/her own arrival or transit. Often exacerbated by poor radio calls and a lack of awareness. Both airplanes bank to miss each other and tempers usually flare afterwards.
Lesson: Fly the standard pattern, making clear position reports. Assume other pilots won’t be so conscientious, so fly defensively. Keep your visual scan going and raise or lower a wing to double check. Have a sense of where each airplane is in the pattern, and if unsure, ask!
4. Runway incursion. Given clearance to cross the runway, as I did so I saw a Falcon 900 barrelling down it. I had been lazy, and was lucky! Turned out he was landing and stopped well short of me, but it was a clear reminder that airmanship is required also on the ground.
Lesson: Trust, but verify. I say to myself “clear left, clear right, cleared to cross” when crossing a runway.
5. High density altitude take-off. The first take-off at an airport above 5,000 ft. is a real attention-getter. Combine elevation with high temperature and a non-turbocharged engine and you have a long take-off roll and a slow climb. It’s hard to resist the urge to pull back even more, but don’t!
Lesson: Don’t assume your airplane can do it – build in some healthy margins. You can’t make the airplane fly if it doesn’t want to.
6. Falling asleep in flight. You close your eyes for a moment …. When you wake up, you instantly look to the fuel gauges and GPS. You call ATC to make sure you didn’t miss a radio call while you were “off air.” It may have only been seconds, but you’ll remember the scary feeling forever.
Lesson: The old “eight hours bottle to throttle” is a bare minimum. If you’ve been working hard or playing hard, make an honest assessment of whether you’re safe to fly. When in doubt, delay the flight.
7. In-flight icing. A frightening event for most pilots, especially in airplanes with no de-icing equipment. Whilst we’re getting better at forecasting ice, the when, where and why it happens is still a mystery to many.
Lesson: If the temperature is below 5C and/or you’re in cloud, be alert. Learn to read Nature’s signs of possible icing: Lows, temperature inversions, strong lifting forces etc. Look for reports of cloud tops so you know whether getting on top is an option. Do not linger in ice, even with de-icing equipment. Execute your backup plan immediately (you do have one, right?).
Any of the above ring a bell?
Thursday, 1 September 2016
(Acknowledgements: AIR FACTS/Richard Collins)
Here’s Richard’s view of the 3rd. pre-requisite of Smart Piloting …..
Pat your head and rub your tummy…
When I was a kid I heard that one item of screening for potential military pilots in 1938 was to be able to pat your head with one hand and rub your tummy with the other, and then switch without missing a beat.
What does that have to do with flying in 2016? A lot, because operating a private airplane has come to require more and more coordination as time has passed. Now it has become a matter of getting all your stuff together before a flight and keeping it together.
Next time you ride on an airliner, note everything that happens before, during and after the flight. Note how many people it takes. Then, next time you prepare for a trip in your airplane, remember that everything you saw done has to be done for your own flight by one person - you. That is why coordination is such an important piloting skill. Known poshly as CRM (cockpit resource management), it means the effective use of all personnel (including any with local experience or knowledge who may not actually be travelling with you) and material assets available.
Preflight work is pretty standard. Plan the flight, check the weather, check the airplane carefully, load everything properly, run the checklists, get a clearance (if IFR, or required for VFR) and you are ready to fly.
However, there is a special element requiring coordination when considering your route v. weather. In flat country the weather is the prime consideration, but in hilly terrain the interface between the two has to be considered. The hard part is coordinating the arrival with known weather conditions. So don’t just plan the weather, but plan how the weather and the terrain work together.
Also requiring coordination is the relationship between your altitude and the distance to fly to touchdown. This ratio can get pretty ridiculous at many mountain airports, and if you haven’t done your homework the approach can become a muddled high and fast affair. So do a thorough pre-flight survey of the departure and destination airfields to determine the existence of any out-of-the-norm departure and arrival procedures set up by those who know in order to counter problems inherent in the terrain. A lot of airplanes have been lost because the crew was unaware of the terrain or the procedures at one end or the other.
I’ve told of this before but when on the subject of coordination, it is worth repeating. Concorde flew its whole life with the original avionics. There were none of the modern whistles and bells. I watched in wonder many times as a captain coordinated everything about an arrival. From almost 60,000 feet at 1,150 knots, he had to prepare for it even with the airplane still at the gate at JFK. I watched a number of them do that using the best computer of all, the old brain.