Emergency descents

Every airplane, of course, has an engine-fire checklist, but pilots should not waste valuable time looking for and reading it during such an emergency. The initial steps should be committed to memory. After shutting off the fuel supply, descend, land, and evacuate immediately. The urgency of this advice holds even if the fire seems to have been extinguished because even an airspeed change can rekindle a smoldering fire with a vengeance.

An expeditious landing first requires an expeditious descent. Unfortunately, the pilots of most aircraft are not offered advice about the best way to get down in a hurry. Intuition tells us to simply chop the power and shove the nose down, but this maneuver can be more involved, especially when descending in a complex airplane.

An emergency descent with fixed landing gear is relatively simple: close the throttle, advance the propeller-pitch control (if available) to maximize drag, and head down at redline airspeed.

But when diving an airplane with retractable gear, does the maximum rate of descent occur at high speed with the wheels in the wells or at a lower speed with the gear extended to add drag?

Some helpful advice can be obtained from the emergency procedures developed for pressurized airplanes. Checklists for these aircraft detail the steps required to make a rapid descent in the event of cabin decompression. Because a medical emergency or a fire at altitude also can require an emergency descent, similar guidance should also be provided to pilots of nonpressurized aircraft, but it usually is not. The recommended way to make an emergency descent in a Beechcraft Baron 58P, for example, is to push the propeller controls fully forward (flat pitch), close the throttles, establish an indicated airspeed of no more than 175 knots, lower the landing gear, and extend the flaps 15 degrees. The result is an almost 4,000-fpm descent.

However, the same maneuver in a Cessna 421C Golden Eagle is performed clean (gear and flaps retracted) and the nose pushed into a dive at 240 knots (V_NE). In turbulence, though, reduce to 146 knots and descend dirty (gear and flaps extended).

The difference in the two procedures reflects the difference in limiting airspeeds. The Baron has relatively high gear and (partial) flap extension speeds. The Cessna has lower limiting speeds. As a result, it cannot descend as rapidly when dirty at 146 knots as it can when clean at 240 knots.

When needing to make a rapid descent in an airplane for which a procedure has not been developed, dive clean if gear and flap speeds are relatively low and dive dirty if gear and (partial) flap speeds are relatively high.

One of the most difficult aspects of an emergency descent with a fire is slowing in time to make a survivable landing. Some years ago, a friend, Eddie Grant, was flying his Beechcraft Bonanza A35 from San Francisco to Santa Monica. During cruise, an engine fire developed because of a fuel leak. Grant headed for nearby Paso Robles Airport (PRB) at high speed while overflying several emergency landing sites. When the aircraft was on short final, horrified observers watched an inferno erupt under the cowling.

The aircraft shot across the runway threshold at extraordinary speed. The right-seat passenger opened the cabin door before touchdown to escape the flames and was killed in the process. The Bonanza landed on its nosewheel and began cartwheeling into a smoldering aluminum ball, claiming the lives of its pilot and rear-seat passengers.

An engine fire creates an urgent need to land and evacuate, but a pilot must exercise the discipline needed to slow down in time to perform a survivable landing. With a fire urging haste, this is easier said than done.

Preventing an in-flight fire obviously is preferable to coping with one. Performing a methodical preflight inspection can minimize the risk of fire. Pilots should be on the alert for puddles, streaks, and stains of fuel, oil, and hydraulic fluid, both under and inside the cowling. Check on the security and condition of fuel and oil lines. Also, tug gently at the end of each exhaust stack to ensure it is not cracked and loose. Exhaust leaking from a cracked stack is an excellent source of ignition for an engine fire.

Never trust in luck and the statistical infrequency of an engine fire to insulate you from such an emergency. A sudden gush of flame can be harsh notice that your luck has run out.

www.BarrySchiff.com