CFI to CFI
Don't mess with proven procedures
|If I am going to deviate from the manufacturer's recommendations in the operation of an aircraft, I need a very good reason to do so. Developing a unique personal checklist may seem like a good idea, but beware of the pitfalls.|
On January 17, 2008, a British Airways Boeing 777 experienced loss of power in both engines on short final to Runway 27L at London Heathrow. The ensuing dead-stick landing was successful by most standards, and the widebody jet skidded to a stop on airport property partially on the runway threshold. Fortunately, there was no fire, and although the aircraft was damaged beyond economic repair, only one serious injury and 12 minor injuries were sustained by those on board.
During the ensuing investigation, the AAIB (Aircraft Accident Investigation Board, the U.K. equivalent of the NTSB here in the United States) focused on water in the fuel, which had developed into a slushy mixture during extended time at high altitudes in the polar region as the aircraft flew from Beijing to London.
During the ground evacuation, rescue personnel noted that a large quantity of jet fuel was being pumped from one of the engine spar valves, which remained in an open position--even though closing it was one of the items on the evacuation checklist that had been completed in its entirety before the cockpit crew left the aircraft. Although not causal to the accident, this might have had dire consequences if fire had broken out during the evacuation.
A closer look at British Airways procedures revealed that it had changed Boeing's evacuation checklist in an effort to split evacuation duties between the two pilots. Although Boeing had raised no technical objections to the change, the revised procedure left open the possibility that the items on the checklist could be performed out of sequence, thus leaving a fuel pump powered and a spar valve open when everything else had been shut down. Unbeknownst to the crew, this is exactly what happened when the captain pulled both fire handles before the co-pilot moved both of the fuel control switches to cutoff.
In the somewhat more lax operations that we encounter in general aviation flight instruction, I see many pilots and flight instructors making their own checklists. These range from simple before-engine-start checklists to complex revisions of the entire pilot's operating handbook (POH).
While these deviations from the manufacturer's guidance may be well intentioned, careful attention must be paid to checklists supplied by the manufacturer. Now I am the first to admit that as much as I've searched, I am unable to find a manufacturer's checklist (or for that matter, a POH) for the 1941 Piper J-3L-65 Cub that I fly. I'm confident that the five or six items that I penciled in on the back of a business card and tucked into a crack in the sidewall do not convey bad information. However, I raised an eyebrow at a homemade laminated checklist that I found in a late-model, high-performance single recently, on which several dozen items had been added to the checklist included in the POH. If I am going to deviate from the manufacturer's recommendations in the operation of an aircraft, I need a very good reason to do so.
One cold day this past winter, I arrived at the aircraft to conduct a lesson with a student who had preflighted the airplane using a checklist of his own making. Noting that the flaps were down for the preflight even though this was not mentioned in the POH, I was further surprised when, before engine start, the flaps were retracted! You guessed it--the single-digit outdoor temperature had taken its toll on the battery. Operating the flaps was the extent of the power it had left.
We cooled our heels for a few hours inside while the battery charger did its work. This gave us plenty of time to go over his homegrown checklist and discuss the finer points of where items he'd included on his checklist could get him in trouble.
A manufacturer's checklist for late-model current production aircraft has likely been vetted by experts from the engineering department as well as legal. Tread lightly if you are pitting your expertise against the manufacturer's.
Jonathan J. Greenway is chief flight instructor for the AOPA Air Safety Foundation. Formerly a captain and check airman for American Airlines, he has been an active CFI since 1980 and has approximately 13,400 hours.
By Jonathan J. Greenway