I've experienced maximum breaking in an emergency landing.
Many passengers (including me) instinctively put their hands on the seat in front to steady themselves. You could easily slide around if the seat belt were loose.
It was it worst for children whose legs didn't reach the floor, but there were none seated near me.
A long time ago I was on a FAA certification test flight where we tested maximum braking. I wasn’t in the flight deck, so I don’t know if it was literally true, but it was described as “pilot standing on the brakes” and it sure felt that way. All our equipment was strapped down and when the pilot hit the brakes for our first test my glasses flew off my face. Those brakes are no joke
Maximum breaking, is powerful stuff… Real red hot metal and tolerances engineering stuff. You have to be able to stop the airplane at it’s maximum take off weight at the maximum takeoff ground speed (got to account for tail winds) within the acceptable safety stopping distance on the runway, and they have to sit there after this without any help for several minutes to represent the time it can take to scramble ground safety and rescue crews to assist... On big jets this involves sacrificing the breaks and often even the tires, as the breaks get glowing red hot and the heat radiating off them will be strong enough to heat up the air in the planes tires to the point that safety systems like fusible plugs/patches designed to melt (but not break from normal pressure) kick in and the tires blow out the plugs and deflate due to the exposure to sheer heat coming off the breaks as they sit there for a few minutes soaking in the heat from the red hot breaks…
Definitely a much better view of the brake assembly and the extreme forces they deal with. I’d forgotten how much the sound reminds me of a sort of bad off key imitation of the “Deep Note” Dolby THX intro sound. As the rotation speed slows it pitches down the frequency scale into more audible tones and sounds slightly louder as the microphone picks it up better and then it fades out towards the end.
I do think it even though it’s a better brake mechanism video it’s not quite as visually impressive as watching a 747-8 just about to nose up suddenly nosing down as it slams on the brakes and they come to a stop in a dissipating cloud of smoking revealing the red hot brakes glowing in the wheels.
I was on a plane that had engine issues during takeoff, front wheel off the ground. We slammed back down to earth and likewise they braked harder than I'd ever experienced. Lady's phone flew out of her hand. It was intense.
Wow. That's almost unheard of. There's a speed called "V1"; this is the last possible moment for a pilot to start aborting the takeoff. There's another speed called "Vr", which is when the pilot starts the rotation (lifting the nose off the ground) [1]. Vr is higher than V1. Past V1 its unsafe to abort, even if a tire blows or an engine fails. The only time it would be aborted would be if the pilot thinks the plane is unflyable, such as both engines failing or controls not working.
Ameristar Charters 9363 is one example of this happening:
> Captain Mark Radloff was thus faced with an almost unprecedented situation: having already accelerated well past V1, he suddenly realized that his airplane would not become airborne. At that point he faced a choice — keep trying to force it into the air and risk failing, running off the runway at well beyond takeoff speed, or try to stop, and guarantee a lower-speed overrun?
We were all deplaned after, and they had to find everyone new flights. They wound up getting me a hotel nearby. So I guess it was unflyable? Easily my worst travel experience.
As per the linked website:
" If the airplane reaches a peak speed of only 10 knots beyond V 1, the brakes must now dissipate 20 percent more energy than had the abort been initiated at V 1.
Beyond the fact that there is no certification requirement for the brakes to be able to absorb any energy beyond that existing at the highest weight and V 1 combination demonstrated, there also is no performance data to know how much runway would be needed even if the brakes are able to handle the extra energy. Adding to the chaos, one brake must now absorb all the energy of the aircraft, as the blown tire’s brake has been rendered useless."
Basically you'd be unlikely to get the airplane to stop before the end of the runway because brakes are not designed to handle breaking at such speed (keep in mind that an airplane lands at a slower speed than it takes off thanks to the flaps).
The V1 decision speed is not fixed, it's calculated for each take-off based on weight, wind, runway conditions, maximum thrust settings etc.
It meets these constraints:
1. Low enough such that if you try to stop from that speed you will stop before the end of the runway
2. High enough such that if you have an engine failure at that speed, you will make it airborne on the other engine before the end of the runway
3. Not higher than rotation speed (you can't decide to abort after pitching the nose up and getting the aircraft airborne)
4. Not lower then minimum control speed (you can't keep directional control in case of an engine failure below minimum control speed, so your only option is to abort)
If there is no speed that meets all conditions, then your runway is too short and you can't go. Reducing weight helps, since you'll accelerate faster, stop easier, and take-off at a lower speed. So that's usually the solution if your runway isn't long enough.
Constraint 1 is why you're committed to takeoff above V1. If you would try to stop above V1 there is no guarantee that you'll stop before the end of the runway. While you are guaranteed to be able to take-off above that speed, even after an engine failure. So you take the problem into the air, run checks, and return.
Hmm that's interesting since by the time the front wheel comes off the ground, an airplane would normally be past V1 speed and they'd have to commit to the takeoff.
That’s generally true but the rule is that you never abort past V1 unless you have specific immediate reason to believe the aircraft cannot become and stay airborne.
There aren’t a ton of reasons one might think that but a few come to mind like total engine failure or lack of elevator control or similar.
I can only imagine that the pilot had reason to believe something was wrong the moment the forces began to lift the front wheel and change the aircraft dynamics, which definitely is in the extremely fast changing grey zone for a lot of conditions highly dependent on the exact aircraft and it’s current conditions. Light payload and fuel loading pushing V1 very close to takeoff speed and lower than the maximum numbers, headwinds, engine conditions, etc… it’s definitely a case of “sometimes pilots do have to make quick decisions” and my money is on engines or the hydraulics when they first took load on the moving surfaces as the aerodynamics shifted passing V1 towards takeoff speed.
This was the case with Ameristar Charters 9363, which aborted after V1:
> [T]he jammed elevator could only be detected once aerodynamic forces came into play — something which would only happen once the plane was already speeding down the runway. The NTSB was forced to come to an incredible conclusion: that there was no way for the pilots to have detected the problem until they attempted to rotate for takeoff.
In Europe the standard is infant with extra belt. It attaches to the parents belt. Some US based airlines offer this as well, but it's not mandatory by the FAA.
You can use a car seat on a plane. It's an absolute pain in the arse and almost entirely unregulated, I've seen various 'rules' like 'must be forward-facing', 'must be rear-facing', 'must be 5-point harness', 'must be 3-point harness', 'must be no more than 41.5cm at its widest point', 'must have "certified for aircraft use" printed on it', and so on.
But it is technically possible to take a child on a plane in a car seat, if you can find a suitable plane, suitable car seat, and suitable child.
Many passengers (including me) instinctively put their hands on the seat in front to steady themselves. You could easily slide around if the seat belt were loose.
It was it worst for children whose legs didn't reach the floor, but there were none seated near me.