Contents

Notes…
No 'fast hands' is good advice in an aircraft emergency.

Don't just do something, sit there.

Air Force: Wind the clock.

X. AREA OF OPERATION - EMERGENCY OPERATIONS
Task: 
EMERGENCY DESCENT
REFERENCES: AC 61-21, operating handbook, flight manual

EMERGENCY DESCENT
Reasons for an emergency descent. Leave 3000 feet for 1500 feet in power dive as though having engine or cockpit fire. Compare with power off nose high slip to lose altitude.

P 1. Knows and can discuss factors of urgency, aircraft limits, and techniques relevant to both emergency descent and survival.
P 2. Recognizes the urgency of an emergency descent.
P 3. Establishes the recommended emergency descent configuration and airspeed, and maintains that airspeed, + 5 knots.
P 4. Demonstrates orientation, division of attention and, proper planning. No descents below 1500' or above Vne
P 5. follows the appropriate emergency checklist.

EX The nature of the emergency helps decide the best descent procedure. A major cockpit or fuel fire would require a Vne descent. An engine fire could be kept away from the cockpit by a nose high, power-off, slipping descent. A descent through an overcast of unknown base might require slowing to Vmc with power on to control the descent and hands-off rudder flying for heading. A black hole situation would use a similar descent where the surface was unknown. A descent through a hole in an overcast could be made with full flaps and power off in a descending spiral with flap removal below the bases to expedite the descent. There are probably more.

To get down quickly you must reduce power and create as much drag as possible. The emergency descent is found under Task A of Emergency Operations in the private pilot PTS guide. Unfortunately, most light aircraft POHs do not contain information on emergency descents.

There are several emergency descent procedures that can affect the technique selected. An engine fire in a fabric aircraft would give the nose-high slip as a means of keeping the fire from the fabric. If you were directly over a good landing site then a high-drag descending spiral would be best. I have tried descents with and without flaps and find that there is little or no difference in the descent times per on-thousand feet. Kershner suggests a spin down to 1000' as a good option.

In no case should you exceed the V-speeds during the flight test. Examiners expect the pilot to put the aircraft into a high drag configuration and initiate a maxim rate of descent close to but not exceeding any critical speed.  Maximum G-load on flaps is 2-Gs.

The fact is that any extended emergency descent poises an engine-damaging problem due to shock cooling. Explain to the examiner that you will terminate the maneuver after you have completed any POH prescribed procedures and established a stabilized descent. When you are faced with the need for an emergency descent you have several options that give nearly the same rate of descent for the required 1500' altitude loss.

Procedure #1
Carburetor Heat, power off or on and descend at structural cruise speed (where the yellow and green meet). Descent should level off after losing 1500' and no descent below 3000'. This descent is at a relatively high speed and covers considerable distance. On arrival at the 1500' descent point you are going so fast that even more distance (read time) will be required for any landing. This is not the descent you would use to get below a cloud deck. It is visually very difficult to tell your relationship to clouds. Clouds are all of indeterminate size and distance you are quite likely to reach the clouds before getting below them.
Procedure # 2
Carburetor heat, power off, at white arc put in full flaps and descend at top of the white arc. This descent will get you down in the same amount of time as #1 but has the advantage of covering less distance (where distance is not a factor) and your lower speed will allow rapid deceleration to a landing speed.
Procedure # 3
Carburetor heat, power off, enter a full slip into your best estimate as to wind direction. Depending on the wind velocity the descent can be anywhere from straight down to an angle approaching that with full flaps. Not to demonstrated with flaps but will be useful information in a true emergency.
Procedure # 4
Carburetor heat, power off, at white arc put in full flaps while initiation a turn of not over 45^ while maintaining airspeed at the top of the white arc.

Emergency Descents (From FAA text)
An emergency descent is a maneuver for descending as rapidly as possible to a lower altitude or to the ground for an emergency landing. The need for this maneuver may result from an uncontrollable fire, a sudden loss of cabin pressurization, or any other situation demanding an immediate and rapid descent. The objective is to descend the airplane as soon and as rapidly as possible, within the structural limitations of the airplane.

Simulated emergency descents should be made in a turn to check for other air traffic below and to look around for a possible emergency landing area. A radio call announcing descent intentions may be appropriate to alert other aircraft in the area. When initiating the descent, a bank of approximately 30 to 45-degrees should be established to maintain positive load factors ("G" forces) on the airplane.

Emergency descent training should be performed as recommended by the manufacturer, including the configuration and airspeeds. Except when prohibited by the manufacturer, the power should be reduced to idle, and the propeller control (if equipped) should be placed in the low pitch (or high revolutions per minute (RPM)) position. This will allow the propeller to act as an aerodynamic brake to help prevent an excessive airspeed buildup during the descent. The landing gear and flaps should be extended as recommended by the manufacturer. This will provide maximum drag so that the descent can be made as rapidly as possible, without excessive airspeed. The pilot should not allow the airplane's airspeed to pass the never exceed speed (VNE), the maximum gear extended speed (VLE), or the maximum flap extended speed (VFE), as applicable. In the case of an engine fire, a high airspeed descent could blow out the fire. However, the weakening of the airplane structure is a major concern and descent at low airspeed would place less stress on the airplane. If the descent is conducted in turbulent conditions, the pilot must also comply with the maneuvering speed (VA) limitations. The descent should be made at the maximum allowable airspeed consistent with the procedure used. This will provide increased drag and therefore the loss of altitude as quickly as possible. The recovery from an emergency descent should be initiated at a high enough altitude to ensure a safe recovery back to level flight or a precautionary landing.

When the descent is established and stabilized during training and practice, the descent should be terminated. In airplanes with piston engines, prolonged practice of emergency descents should be avoided to prevent excessive cooling of the engine cylinders.

Emergency Addendum
There is good reason for those who advocate making training takeoff climb-outs at Vx. Vx will get you high while relatively close to the runway. Your return to the runway turn is a more viable option than were you to climb-out at Vy. In any event you do not want to waste of your four seconds thinking about what to do. Get the nose down and on the way down make your decision. Straight ahead is historically the best survival way. Getting into the 45-degree turn into any wind will be the most practical way to get around with the nose down. The four-seconds is the mathematical time it takes a climbing C-172 to reach stall speed once the engine fails.

In any emergency, make what you do as near normal as you can. Don't do anything new or strange. The familiar will make things easy. In a controlled situation don't ask. Tell the facility what you are planning and going to do. By declaring an emergency you have gained the right to do what it takes to make the safest operation possible.

Emergency Descent Differences
Now required by the PTS, the emergency descent used is specific to the type of emergency. A structural problem requires a different descent than an engine fire, a cockpit fire a different descent from an engine fire and so on. At altitude any descent is going to take several minutes. It behooves the instructor to show the student several modes of descent.

I have timed no-flap high powered speed descents as might be used to blow out flames with full flap power off descents for 1500' land have found that the time involved are within seconds of each other. My leaning is toward the use of flaps since it reduces the time and distance required for landing and exiting. Both of these descents can exceed 2000 fpm if performed in a steep bank. If vibration or structure noises get worse in the descent, slow your rate and create as much drag as you can to increase the rate of descent without an increase in airspeed.

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