Tuesday, July 24, 2007

Surviving forced landings




FAA Wings Safety Seminar
Oshkosh - 7/24/07

Presented by: Eric Basile - FAAS team

Forced landings are probably one of the most feared things that most of us pilots think about and fear; second, perhaps, only to fire in an airplane. There are some common things we may not think about ordinarily that will improve your chances of
survival.

In July 2001, two were killed when their Cherokee went down on the way to Oshkosh. The cause was throwing the fuel selector to the wrong position. But the FAA also found there were plenty of spots nearby that could have been used by the pilots to
land safely.

About half of all engine failures are related to causes directly controllable by the pilot. In 2000, most engine failures were attributed to fuel mismanagement (43%), with mechanical failure second at 26.6%. Fuel management is comprised of starvation (there's fuel available for some reason the selector was not selected properly), fuel exhaustion (no more fuel), and fuel contamination.

Most engine failures are not necessarily a point where the engine stops dead. Often, it's possible to obtain partial power from the engine. If you're flying enroute, you don't necessarily need full power to stay in the air. If the engine is still making power, that gives you a lot more options.

There is no reason an engine failure should automatically result in a fatality or serious injury.

PROPER PRE-FLIGHT PLANNING

Know your terrain. This is crucial. Plan your flight over a path that follows a highway or a mountain pass in some locations, such as Colorado, to give you more options.

Don't become GPS dependent. Most people hop in, plug their destination in the GPS and hit "direct." Since nobody draws lines on sectionals anymore, you really don't know the kind of terrain you're flying over. You lose sectional awareness.

I heard of a guy who took off from NW Montana headed for the Midwest. He called Salt Lake Center for VFR advisories in his 172. Center asked for his position and he said, "I'm 818 miles from Lincoln, Nebraska." It just shows how dependent people
have become on GPS.

You can keep an old sectional in your airplane to evaluate options. I recommend using Aeroplanner.com to study the route beforehand. EAA members have free access. When you type your route in, you can overlay your route over any kind of chart
you'd like and it'll print it out in 4 x 6 kneeboard squares. That'll give you a nice 30-mile swath to help you maintain situational awareness as you fly along.

Study the local airport area when you arrive. We are often so focused on what we'll do when we land there, we don't pay attention to what the area is around the airport. But just think of it, you're going to take off again. So if your engine
fails, you're not going to know what sort of terrain is out there. But it's really easy while landing to look around and find places to land if you need to when you take off later.

Plan your routes as best as possible to provide suitable landing areas. You might go toward a bigger airport that has maintenance services.

Consider increasing altitude to provide greater gliding distance. Fly at the highest altitude that's practical. You get better fuel consumption, more options, better radar coverage, better nav reception. There aren't many benefits from flying at
a low altitude.

UNDERSTANDING AIRSPEED

There's more to it than best-glide airspeed. Still, the first thing to do when you think you may have a problem is to establish a glide in the airplane. Pilots are task-oriented people and when the engine makes noise, they start trying to fix
the problem. They divert their attention from aircraft control to fixing the problem. You're wasting time and you're wasting altitude. By establishing the glide and trimming the airplane to stay in that glide, you'll be better off.

Best glide speed gives you the greatest forward distance per unit of altitude loss.

There are some problems with it, though. They're typically only published for maximum gross weight. The problem is best glide speed is not just one speed. It's a function of the weight of the aircraft and that's a problem that not many people
consider. By definition, the only time you can be at max gross is at takeoff.

There's a disconnect between the information that's available and what you need to fly in an emergency. It's almost never going to be "the book number" that's published.

Minimum sink airspeed is a concept integral to glider flying but it's never made it over to power flying. It's going to be critical in an emergency. The purpose of MSA is to maximum endurance, not range (i.e. time in the year instead of distance).

If we lose an engine at 5,500 feet and the landing site is directly below us, we need to maximize the time in the air to maybe get the engine restarted.

Minimum sink airspeed can be calculated as the best glide speed times the square root of your present gross weight divided by your max weight.


(Update 9/27/07: Eric sent me this correction: Published best glide speed for max gross weight X *SQRT* (Actual weight of airplane/Maximum gross weight)
is used to find the BEST GLIDE speed for the exact weight you’re flying at, not minimum sink airspeed.)


One way to establish MSA is to get in your airplane, figure out what your best-glide speed is and take it a few knots slower than that. Slow it again until you get a 400 fpm drop. That's your minimum-sink airspeed. If you slow it down more, you'll
sink faster. But there's a point on the curve that is your minimum-sink airspeed.

Ideally, you'd practice and know this number. But if not, when your engine dies, immediately put it into a glide, and then crank your trim full nose up. The nose will go up slightly and then descend a bit, pick up speed, porpoise a couple of times, and then settle at your minimum sink speed.

We need to eliminate the "rote" level of understanding of best glide speed. Start with the published numbers, but use more intelligence to use the speed that's best for you.

Glide speed can be adjusted for wind. If i'm gliding at a best glide speed of 60 and thee's a head wind. If I have an airport 2 miles away and I'm at 60 in a 50 knot wind, I'm never going to make it to the airport at best glide speed. So the best glide speed isn't always "rote." You have to be the master of your aircraft and you need to do whatever you need to do.

You can increase your glidespeed by half for a headwind. If flying a constant-speed propellor, you need to put your lever full forward. (High pitch-low RPM) to decrease drag. If not, it's going to try to suck all the energy out of the air to keep the propellor turning.

(Update 8:14 a.m. 11/22/08 - Mike Linse of Corvallis, Oregon writes:

This information about the prop speed control is not correct. Lever full forward is the high-rpm, minimum-pitch setting. The high-pitch, low RPM setting is lever (or push-pull control) fully back.)


These are the charateristics we often think about for a good emergency landing spot

1) Far away from the FAA
2) Flat
3) Hard surface
4) Big

Not necessarily. Look at the guy who landed the T-6 on Highway 41 in between cars, and only damaged the right wing on some highway signs.

The goal is surviving the accident, not touching down without damaging your airplane. This is about keeping you and your family safe. Unless the terrain is severe, a good landing spot is probably nearby, that fits none of these characteristics.

We're conditioned to moving foward, we often forget what is behind us.

Tip: Draw an imaginary circle from the spinner to the the wing tip, you will ALWAYS be able to land within this area.

The typical GA aircraft glides at abut 10:1, or 6 degrees. Take your thumb and hold it out at arms length. The distance from your tip of your thumb to your knucles is probably not reachable with no wind. But from your knuckle to the base of your hand
will be reachable.


COPING WITH STRESS


Most forced landing fatalities are caused by failures of the mind, more than failure of the aircraft. Under panic, your actions do not become productive. It locks you up and you're not going to be able to have a successful outcome. You don't just give up your pilot-in-command authority just because the engine quit.

Most people perform better under a small amount of stress. In a complex task or emergency, your performance falls off a lot faster, even with the same amount of stress. So shed things you don't need to be concerned about. Keep things in a process, establish your airspeed, pick a spot to land, and evaluate your progress to the field.

Stress exists. Deal with it by having a rational, systematic approach to emergencies. This is the Air Force philosophy. They have a thing called stand-up where they tkae the new pilots, put them in a room with everybody else -- instructors, commanders, etc. It's intended to be stressful. They'll pick one person out out at random and post an emergency situation to them. He has to repeat the bold-faced procedures. If he screws up or says something out of order. They tell him, "sit down." And he's grounded for the day.

But before he even gets to how he'll handle the emergency, he has to say these words,

"I will maintain aircraft control, analyze the situation and take apropriate action, and land as soon as conditions permit."


Success is as much a matter of the mind as much as it is of piloting skill.

APPROACH AND IMPACT MANAGEMENT

We're going to configure the airplane, circle around, figure out which way the wind is coming, manage the plane to the ground.
I would suggest the idea that you're gloing to plan your approach and if you are too high at your decision point, increase drag or slip the airplane. But you can't do anything being at low. If you come in and bring it high and you don't end up
touching down halfway down and go off the end at a slow speed, that's survivable. Bring it in short and fast, it's a lot less likely to be survivable.

Speed is the thing.

Doubling your ground speed quadrupples the total destructive energy. Reducing it by half reduces it by one-fourth. All the energy has to go somewhere. That's why you must manage the energy all the way to the ground. An impact at 120 is three times
as hazardous as at 70.

General aircraft are designed to decelerate at 9 G's. At 50 mph, you need 9.4 feet to stop an aircraft at a 9G deceleration. From 100 mph, you need 37 feet.

That's why minimum sink airspeed -- not best glidespeed -- should be your speed at touchdown. But not all pilots are comfortable flying at these slow speeds.
Your survival is primarily determined by your speed and angle of impact.

Before touchdown:

Shut off all sources of a postcraft fire (fuel and electricity). Brief your passengers and keep them in the loop. What if you got knocked out? Your passenger will have to shut the master off. Consider keeping the doors shut to maintain cabin integrity. Keep a tool in your plane to bash out a window if need be.

File flight plans and stay in touch. Prepare an emergency survival kit to deal with adverse conditions. If you don't file a flight plan, nobody knows where to look for you. It's cheap insurance to tell someone where you're going.

Low altitude engine outs:

Why do pilots continue to kill themselves by turning back to the runway at low altitude? Few pilots understand how difficult a maneuver this is to perform. If you were at 500 feet, and banked at 45 degrees, you're still not going to be near the
runway. You'll tighten your turn and spin into the ground. It's a high-performance maneuver for which we're completely untrained. The outcomes are so poor that it's better to think of just about any OTHER option than turning back toward the
runway.

If you just look either way at a 60-degree arc, chances are you'll find someplace suitable. In a study of turnbacks, they said only 62% were successful, but even this statistic is lying. They put pilots in a simulator and gave them an engine failure. Thirty-some percentage of the turnbacks were successful, and even after repeating over and over again, they could only get 62% to be successful, whereas those who chose to land straight ahead were successful 100% of the time.

Have a plan for engine failure on departure. When it occurs, it's too late to come up with a plan. Monitor your airspeed on climbeout. Stalling is almost always fatal.


PRACTICE

Under periods of high stress... we do not rise to the occasion -- but instead sink to the level of our proficiency!

Get together with your favorite CFI and talk about these things. Talk about minimum-sink airspeed. Practice spiralling descent from cruise altitude, how to do a rollout etc.

QUESTIONS AND ANSWERS:

Q: What about at night?
A: Only about 10 percent of flight activity happens at night. Plan your flight to go along the edge of populated areas.I'd suggest landing NEXT to a road because there's probably a field there (don't land right next to the road because of
powerlines).

Let's say you had a choice between trees and water. I'd choose trees. If you land in water, your plane is probably going to flip and fill with water. And there you are at night, with water coming in, in an unfamiliar environment.

Q: With a retractable, leave it down or up?
A: The idea on a hard surface, leave it down. Soft surface, follow your POH. A lot consider leaving it up to keep the plane upright and decelerate on the belly.

Note: To view a powerpoint presentation, go here.

1 comment:

  1. Excellent presentation. Thank you

    ReplyDelete