Learn › Maneuvers › Emergency Descent

Emergency Descent

Some emergencies you fly out of; a few you can only get down from. An emergency descent trades altitude for time as fast as the airframe allows — and the whole skill is doing it without creating a second emergency on the way down.

Emergency Operations — FI.XII.A

Why the maneuver exists

Smoke coming out from under the panel. A cabin that loses its pressurization at altitude. An engine fire the checklist has not put out. These are the emergencies measured in minutes rather than miles, and for every one of them the most useful thing a pilot can do is be lower — lower where the air is breathable, lower where a runway is reachable, lower where a fire has less flight time left to work with.

So the goal is easy to state and harder to fly: lose altitude as quickly and as safely as possible while avoiding further hazards. The airframe has a speed limit, the ground has a floor, and there is traffic in between. A descent that breaks any of those has not saved you anything.

Most training airplanes are not pressurized, so the reason you practice this in a trainer is fire — and the habit. The airplane you fly later may be the one where the cabin altitude climbs and your useful consciousness is measured in seconds. The maneuver is the same maneuver.

That case comes with an order of operations worth learning now, because it is not the order instinct suggests. In a loss of pressurization, oxygen comes before the descent: the crew mask goes on first, then passenger oxygen, and only then does the airplane come down. A pilot who starts down first may not be conscious for the level-off. The descent is what buys back breathable air; the mask is what keeps you flying long enough to reach it. If the emergency is smoke or fumes instead, masks and smoke goggles come out at the same point in the sequence, if the airplane carries them.

What the bank is for

The instinct is to pull the power and push the nose over. That gets you down, but it unloads the wing toward zero or negative G — which floats loose items and people off their seats, can interrupt fuel flow, and gives you nothing to work against while the airspeed runs up.

Rolling into a bank of roughly 30 to 45 degrees solves it. In a bank, part of the lift vector is turned sideways, so the nose falls of its own accord and the descent rate builds while your control input stays a pull. That is the stated reason for the bank, and it is the whole reason: the descent is flown at a positive load factor rather than an unloaded one. Steeper than 45 degrees and you are managing an overbanking, overspeeding airplane during an emergency, which is not the moment.

Flying it

Every step below has an airplane-specific number or setting attached to it, and those live in your POH and on your checklist, not in a lesson. What follows is the shape of the maneuver.

1. Oxygen first, if the emergency calls for it. Pressurization loss, smoke, or fumes: mask on, then fly the descent.
2. Clear the area. You are about to occupy several thousand feet of airspace below you, and nothing you have looked at recently is down there.
3. Power to idle.
4. Mixture as required for the descent, or to the position your checklist calls for if the emergency is an engine fire.
5. Configure per the POH. Gear and flaps add drag and let you descend steeply at a lower speed — but only inside their limiting speeds, so check the number before you touch the handle. Many constant-speed-propeller checklists also call for the prop control forward, where a flat, fast-turning propeller adds drag. Whether that step appears at all, and where it falls relative to the power reduction, is your airplane's business, not a universal rule.
6. Roll to 30 to 45 degrees of bank and let the nose down to the target airspeed.
7. Hold the airspeed your POH gives you. The ACS tolerance is +0 and −10 knots. The plus side is zero because the number was handed to you rather than chosen by you: in one airplane it is Vno, in another a gear or flap limiting speed, in another a recommended figure that sits well below any limit. Which one it is in the airplane you fly is worth knowing before the day you need it.
8. Keep flying the airplane. Altitude, terrain, where you are going, and a call on the radio when you have a hand free.
9. Level off at the planned altitude, within 100 feet, and add power before the airspeed decays.

If there is fire, the descent is being flown to get the airplane on the ground, not merely lower. A sideslip can help keep flames and smoke away from the cabin, and the fuel to an engine fire gets shut off by the checklist, not by improvisation.

What goes wrong

The most common failure is the one that starts before the descent does: not clearing the area. A steep, fast descent into unseen traffic trades a survivable emergency for an unsurvivable one.

Next is overbanking and overspeeding — the bank creeps past 45 degrees, the nose drops further than intended, and the airspeed goes through the top of the range while you are busy with something else. The fix is to treat bank angle and airspeed as things you fly deliberately, not things that happen to you.

Checklist discipline collapses under stress. People fly the descent beautifully and never actually deal with the emergency that caused it, or configure the airplane from memory and exceed a flap speed doing it.

The opposite failure is fixation — staring at the airspeed indicator or the altimeter while the airplane drifts into terrain, out of the practice area, or past the altitude you meant to stop at. Failing to level off is what that looks like from outside, and it is not a soft error: the level-off is a skill element in the ACS with a 100-foot tolerance on it, so it is measured rather than merely mentioned.

Finally, communication. Nobody knows you are descending unless you tell them, and a controller who knows can clear the airspace under you and find you a runway.

After the descent

The maneuver is not over when the descent stops. Once you are level, stabilize the airplane and the systems: re-trim, reconfigure, restore power, and complete every checklist the emergency calls for, including the ones you skipped on the way down.

Then make the decision the descent bought you time for. Nearest suitable airport, weather there, terrain between here and there, fuel remaining, and whether this ends as a diversion or an emergency landing. An emergency descent is rarely the last thing that happens on a flight — it is the thing that gets you into position to handle the rest. Pulling up nearest airports and their current weather is one fewer thing to assemble by hand while you fly, though the flying and the deciding are still yours.

Where you meet it next

On the checkride, the emergency descent is an Emergency Operations task, and the evaluator is watching for the clearing turn, the configuration in the right order, the airspeed held at +0 / −10 knots, and a level-off within 100 feet of the assigned altitude — in other words, that a maximum-performance descent was still a controlled one.

In the airplane, you will recognize the feel of it from steep turns: the same positive-G bank, the same discipline about not letting the nose or the bank get away from you. The reasoning behind the oxygen step belongs to the supplemental oxygen and cabin pressurization lessons, and the failures that send you down in the first place are the ones covered under systems and equipment malfunctions. If the descent ends with a dead engine and a field below you, emergency approach and landing picks the story up from there. They are all in the ground school library.