BUMMMFITCHH

BUMMMFITCHH is one form of a mnemonic used by air pilots to remember the sequence of actions required when an aeroplane is about to be landed.

The checklist

Many of the steps in the pre-landing checklist are double-checks to eliminate the possibility of unexpected failure of the aircraft. Other steps convert the aircraft from a configuration that is optimised for economical flight to one that is safest for landing. Since landing is the most dangerous stage of a flight, it is important to be pre-warned if an engine failure may be likely to occur, and to have a chance to deal with any problem at this point.

The checklist of actions is given below in its most complete possible form.

O-B-U-M-M-M-P-F-F-I-T-C-H-H

* 'O' - Open carburettor heater. This is a device to warm the air intake to the engine, which may otherwise ice up as the aircraft enters more humid air at lower altitudes.

* 'B' - Brakes free. The pilot depresses the rudder pedals, which also act as the brake pedals. This ensures that the brakes are unlocked.

* 'U' - Undercarriage down and locked. The pilot causes the undercarriage to extend, and checks the indicator to confirm that it has locked in place. In the case of a light aircraft, the undercarriage may be permanently extended, but it is good practice to retain this step in the checklist.

* 'M' - Mixtures. The pilot ensures that the fuel/air mixture is at its richest setting, to avoid the possibility of engine failure. During normal flight, the fuel mixture is typically "leaned out" for economy.

* 'M' - Magnetos. Check that the magneto is activated, so that the aircraft batteries are being charged.

* 'M' - Masterswitch. Although it is unlikely that the masterswitch has been deactived during the flight, it should be checked at this point so that all electrical systems are active.

* 'P' - Propellor Pitch. Check to ensure this is correctly set for landing.

* 'F' - Fuel. The pilot checks the fuel levels indicated in each tank (typically one in each wing) and turns the fuel source switch so that fuel is being taken from both tanks.

* 'F' - Flaps. The wing flaps are extended, possibly in several stages. At each stage, the nose of the aircraft will point further downwards, giving the pilot a better view of the runway, and some of the aircraft's speed will be converted into lift.

* 'I' - Instruments. The pilot looks at the relevant instruments (altimeter, artificial horizon, rate of descent indicator, and so on) to confirm that they appear undamaged, and are giving sensible readings. Check heading to ensure aircraft is on the right approach path.

* 'T' - Temperatures and Pressures. The pilot checks the engine temperature and oil pressure in case of an incipient problem.

* 'C' - Close carburettor heater. The carburettor should be warmed by now.

* 'H' - Hatches. The pilot checks that hatches, that is the doors of the aircraft, are safely closed. The impact of landing might otherwise cause a hatch to come open, with possible disastrous results. Also, when properly closed, the doors form an important part of the structurate strength of the aircraft.

* 'H' - Harnesses. The pilot checks that all crew and passengers are securely fastened using their harnesses or lap-belts. This step may include illuminating the signs saying "Return to seat. Fasten seatbelt. No smoking.".

References

Aviation checklists are part of aviation folklore, and therefore references are few and far between.

* Discussion on [http://forums.flyer.co.uk/viewtopic.php?t=43550&postdays=0&postorder=asc&start=0 flyer.co.uk]
* Hints to flying instructors on [http://www.flightinfo.com/instructorhints.htm flightinfo.com]