Extra power needed
Well, if they built parking brakes into these things, one wouldn’t have to bother with the chocks at all! Actually, I assume airliners do have hand brakes, otherwise how would they be able to pull off maneuvers like these here?
Well, if they built parking brakes into these things, one wouldn’t have to bother with the chocks at all! Actually, I assume airliners do have hand brakes, otherwise how would they be able to pull off maneuvers like these here?
Irony, I hope? Most aircraft do have handbrakes. Cessnas and Pipers certainly do. Chocks are only used as and extra safety measure if the handbrake would fail or not be enough (think prop/jet wash, strong winds).
Sigh! Damn! I shouldn’t be writing blogs before I finished my morning coffee, I assume. Just recently drew a strip about the parking brake… I apologize for the mental blackout!
Two other reasons we use chocks instead of the parking brake for anything more than a few minutes:
In warmer weather, there could be a build-up of excessive pressure in the system causing it to fail.
In colder weather, to avoid having the brakes stick due to water and ice contamination.
Also: many old Piper Cherokees only have a handbrake lever, no toe-brakes. The parking brake is a button to lock the lever in place, and you’d use it anytime you have to stay stationary. No differential braking as well.
2 out of 3 Cessnas I have flown in the past had parking brakes that didn’t work, especially the ones with the button to hold it in place…. 😉
Man that video almost looks like the insanity of landing at Kai Tak.
OK I have to add this in here.
When I was a kid in the ’70s my folks ran an FBO in Eugene OR. One day a customer came in, paid for his radios (we did mostly avionics) and left. A few minutes later we heard the plane (a Cessna 172 or something like that) start up. Then the engine got really loud, we looked at each other as it echoed through the hanger. Then there was a bang and the plane taxied away. We went outside and found he’d pulled the chocks and removed the tie-downs from the wings but not the tail. He flew off with our clip hook and a couple of links of the chain hanging from the tail. Apparently stopping to find out WHY the plane didn’t want to move never occurred to him.
Actually, small airplanes only use parking brakes for short periods of time – for example, when running engines checks. When they are parked in hangars, their parking brakes must be released, so that hangar personnel can push the aircraft around. In fact, I remember one time, when a pilot got off his Baron, left the parking bakes on, and went home. When the guy taking care of the hangar that day tried to push the airplane to put it indoors, he went nuts. Luckily, we could call the pilot back quite quickly.
The strip also reminds me of a mechanic I saw once. When performing a 50 hour check on a light trainer, he started up the engine, and then went outside, with the engine running, to operate the throttle from the outside – with nobody else at the controls. And the airplane didn’t have parking brakes, so the only thing holding it against a hangar full of airplanes was two pairs of wooden chocks. Every time he pushed the throttle to the max, we almost soiled our pants. o.O
Interesting to see how the use of chocks/hand brake varies in the experience of different pilots. I guess it has a lot to do with the operating circumstances you are under. We use the parking brake most of the time when the aircraft are left on the apron but then again we have no need to lock the door(s) in our field. I would never trust the parking brake on run-up, I have seen them fail (or just being poor) to many times for that and I want to be really certain that I’m not going anywhere off the map while I’m looking down at the engine gauges 🙂
Just to clear things up: Airliners like A320, A330 and A340 have a small handle at the back of the pedestal which even when the aircraft is completely powered-off, you can still apply the parking brakes. it involves using left-over pressures from the Accumulator (hydraulic pressure reservoir) which allows you to apply the parking brakes for at leaset 3-4 times. After that, all you need is just switch the aircraft on for a minute and press the hydraulics button to energize the pumps for a few seconds and give it some pressure.
coming to think of it… sometimes it’s not as different from Cessnas, Tecnams and pipers 😉