As noted above, the regs require the crew be certain of all aspects of the aircraft’s mechanical condition before flight. The exterior preflight inspection is typically part of that process.
For US airlines the FAA & each airline agree to a particular set of supplementary regs which fill in some of the details in the basic Federal CFR regs. Overall there’s a single master template which the FAA applies to every airline, but it’s like a buffet, where each airline chooses *a la carte *which items it will operate under. Once agreed, these are called Operations Specifications and carry the force of law.
The actual legal requirement to conduct an exterior preflight as such is contained in the Ops Specs. Interestingly Southwest, in the interest of saving time & money, got an Ops Specs exemption to only do this once a day rather than before every flight. No other US carrier I’m aware of is authorized to take this safety shortcut.
I’m a commercial airline pilot, and a FO. The walkaround is usually the FO’s (co-pilot’s) job. Sometimes a capt will do it to stretch his legs or to burn a quick one on a turn, which is appreciated. For my company, a walkaround is supposed to be completed after each and every flight, with a more detailed inspection required for the first flight of the day for that aircraft, or if the aircraft had just come out of maintenance.
In general, we’re looking checking condition, and looking for any damage that might have occurred in flight or on the ground. Off the top of my head, here are some of the things in my mental list, beginning as I stand on the ground by the passenger door, moving clockwise around the plane: (this is not a complete list)
Pax door: cables free, not binding, door level strap in place, no obvious damage. I’ve found frayed cables that had to be replaced, damaged door seals
Nose fuselage: Check condition of: Pitot tubes, angle of attack indicators, static port, oxy blowout indicator. Here’s an an example of damage found by a preflight walkaround TSA Snafu Grounds Nine Planes at O'Hare Field - ABC News
I’ve found hail damage, lightning strike damage, blown oxy indicator, bonding straps missing, radome latches broken, taped over static port
Nose gear: Downlock pins removed, door condition, strut extension, tire condition, shimmy dampers, no leaks, scissor assembly, Overall condition.
Found: Bald tires, slashed tire, flat strut, damaged door, downlock pin in place.
Fuselage from nose to wing: Intact, no dents or scratches not already accounted for in the aircraft logs.
Wing: Emergency lights, taxi/recog lights, wing inspection lights in good condition. Inspect refuel/defuel panel, inspect leading edge for damage, anti ice vents clear of obstructions, naca vents clear, wingtip condition, static wicks, nav lights, aileron flap and spoiler condition.
Found: Twisted flap, melted lights, lightning damage to wingtip, dozens of bird suicides, missing static wicks, small aerodynamic fairings missing.
Main Gear: brake condition, strut extention, downlock pins removed, tire condition, wheelwell condition, uplock condition.
Found: Worn brakes, worn tires
…anyway, I could go on, but I figure that’s enough tedious listing of things to look at. Most days, a walkaround doesn’t reveal anything surprising, but it’s entirely possible to find something broken or in need of attention. Most of these sorts of items just have to be documented by maintenance and noted in the log. Some things might require an actual fix.
Also, walkarounds in the pouring rain are a bummer. =)
MH134. Malaysian Airlines A330 out of Brisbane, July 18 this year. One of the things they should have noticed was that the plastic covers hadn’t been taken off of the air-speed indicators. (Brisbane had been having a problem with insects). Covers should have been removed by the ground crew. No suggestion that the ground inspection had to be made by “The Pilot”, rather, the flight-engineer or one of the co-pilots.
Not the FIRST criteria. The spark plug piston engines require the fuel to evaporate faster … this lets the engine go to higher RPM’s. Then, it was found the ordinary cracking of the oil gave a gasolene mix that was fine is low rpm’s but the need for power took the engines into ignition advanced high rpm ranges… the ignition advanced to give the charge time to start combusting and still give its energy to the power stroke, right… The simple standard gasolene/petrol was too fast to burn, and the octane rating is a good test to differentiate GASOLENES, even if the volatility and flash point were high enough and indistinguishable between the types. So… the octane rating is the ignition advance capabilty.
Turbines avoid this by having the fuel go around multiple times… so ignitiion advance just isn’t a concept in turbines. The diesel reciprocating engine just injects the fuel at the correct time, and has a lesser max RPM as a result too though . The turbines won’t burn gasolene efficiently as the temperatures aren’t high enough. You can run the engine up with a % of gasolene/avgas in your jet fuel, but you wouldn’t want to fly. With any diesel reciprocating engine, you can have a spark plug ignition system to allow it to use gasolene, but you have deploy clean spark plugs when you change fuel to gasolene and the intermediate compression ratio gives poor fuel economy and power . You could fly empty for a limitted range flight. WW2 Tanks would use gasolene to keep going if thats all they had.
Around here, diesel is now more expensive than gasoline, but at 15% difference, there’s no saving to be made. if diesel is twice the price, then you might start diluting the diesel with gasolene.
I was about to say that I don’t know if SWA pilots even leave the cockpit a lot of the time; they typically pull a plane up, deplane, board and take off in like 20 minutes, and having one of them get up, go out, walk around the plane that just landed, and get back in seems like a time-waster.
The Brisbane wasp nest problem happens so quickly that the covers need to be left on till the last minute, hence they are (should!) be removed by an engineer.
It depends on how the workload is spread out amongst the crew. Where I work the captain can do a quick walk-around, get back to the flight deck and still be twiddling their thumbs waiting for the FO to finish doing what they have to do. We can turn around in about 25 minutes including a walk around.
As for the walk around itself, we are typically looking for evidence of damage, fluid leaks, etc.
I’ve only ever seen a mechanic do a walk around but that’s on the freight side. They are more knowledgeable about the plane than the flight crew. They also get stuck doing things like DNA samples if there’s a bird strike. Who doesn’t enjoy that when it’s 20 degrees on a windy day.
It depends on the ops manual. Our manual says the pilot in command must either do it themselves or delegate it to the FO. We also fly to ports that essentially have no ground support so we have a bird damage procedure to follow if we happen to pick one up along the way.
I fly chartered jets, and my company requires an exterior pre-flight inspection (usually the FO’s job) and a post-landing walkaround. I personally would do both without it being a requirement. Too easy to leave a cover on, an oil access door open or any number of other items.
The jet I currently fly has a requirement that the baggage door be unlocked prior to flight because it’s a means of emergency egress, which is interesting because it was the exact opposite at for the plane at my previous company. The baggage door had to be locked as a hedge against a pressurization leak (my current plane has an interior baggage door which is not to be opened in flight above a certain altitude, thus obviating the need to guard against that sort of leak).
When I was an instructor I had to stop students and rated pilots from taking off on several occasions because they had left a cover on the aircraft. A colleague once (knowingly) allowed a student to take off with the pitot / static ports covered and it turned into a neat lesson on how to land a plane with no altitude or airspeed indications.
Via 30 hours in the back seat of a J-3 with a big haired instructor in the front? I assume this was in faster aircraft because my instructor would have killed me for not aborting if airspeed didn’t go live but this was just PFI.
Are you seeing AoA indicators in that part of the field yet?
I always wondered because I grew up at above 7000’ and people paying too much attention to the visible ground speed and not the air speed too much was one problem.
But accelerated stalls and spins also seemed to be a big problem too which would seem to be easier for a pilot to avoid with AoA indicators.
I haven’t been flying prop planes much at all for years now, so I don’t really know if AoA indicators are turning up in GA. They’ve been in every jet I’ve flown so far.
As for checking airspeed during takeoff (in prop planes), it’s a good habit when done correctly. But when I was instructing so many students had to have their eyes pried away from the instruments. Ideally, you’d want to give it just a quick glance during takeoff. Having said that, in VFR conditions a malfunctioning airspeed indicator isn’t that big a deal.
In jets, an airspeed crosscheck is standard, but then you usually have two pilots. I am qualified as single pilot in one jet, but I don’t like to do it because it makes those kinds of checks much more difficult.
And I just remembered another covered pitot / static story… I once took a student with me to pick up an airplane from a maintenance shop. I had learned the hard way to be extra careful on inspections after maintenance work, but I still missed this one. My idiot mechanic had taped over the pitot / static boom (they’re co-located on many Pipers) using grey tape the exact color of the boom itself. I and my student both missed it, and I have no excuse. That was another teachable moment, and my student got to fly and land with no airspeed or altitude information.
Just before boarding a recent flight I saw the pilot doing this for our flight, wearing a windbreaker emblazoned with “PILOT” on the back in lieu of his uniform jacket.
From what I recall this is one of the most time-honored standard operating practices, and one that the first Wright brother to fly probably followed before that very first flight.
But tradition aside, and in the absence of exposure to combat, what could possibly be sufficiently wrong with a plane that would be found by a cursory external examination? It’s more or less a fairly brief perambulation of the aircraft; it’s not like the pilot is looking at every rivet, is it?
They tend not to be in airliners. The nearest I’m aware of is Airbus aircraft that have a flight path vector symbol on the PFD or HUD. It shows where the aircraft is actually moving and from the difference between the FPV and the nose attitude you can work out the angle of attack but it is not displayed directly. The bigger Dash 8s (300 and 400 series) have angle of attack vanes but no display of AoA for the pilot. I don’t know what Boeings have. BAe146 family don’t have AoA displays but they do have the vanes.
Things you may find on a walk around (most of these have happened to me or people I know):
Engine fire extinguisher over pressure.
Bird in the engine.
Nest in the APU exhaust.
Damage to the angle of attack vane.
Brake fans not working.
Fuel leak.
Hydraulic leak.
Lights not working.
Evidence of tail strike on the tail strike indicator (a brightly painted strip at the point of the fuselage that scrapes the ground during a tail strike.)
Evidence of a lightning strike (small blackened holes.)
Basically there are lots of things that can go wrong with a plane and they will have to happen sometime after the last walk around. So if they can be discovered on a walk around, that’s when they will be discovered.
