VforVendetta

Where did I use the word OVERRIDE? Apply gradually until disconnection, then hold what you've got, reduce or increase it gradually if you need to.

I was a mechanic on this thing and every other boeing except 787 for 12 years. 1000-1200 psi at the wheels you're past wheel lockup. Antiskid intervenes before that. Maybe with very heavy weights youd get that pressure at the wheels. This is where more weight on wheels means more brake pressure can be applied before wheel lockup resulting in more braking power. Anyway, this is way overthinking it.

With 17 years flying Boeing aircraft I think I've run out of ways to surprise myself with autobrakes a long time ago.

Nordhavn

Question for the mechanic. Why do we not arm speed brakes for take off? The RTO procedure for most operators have you manually doing it. It is strange. My systems manual has been gutted and doesn't mention much of anything these days.

Hedley

Thats basically where I stand, having also flown the 777 and 756 plus others. 20 years ago long haul flying was great, however as I have aged, my priorities have changed. I can no longer take the fatigue. Since coming back to the 737 I sleep normal hours, exercise regularly, my weight/BP is right where it should be and I feel so much better. Since I won't fly at night anymore, that leaves only the 737 and the bus. On the 737 I get lines with no more than 2 legs per day, no duty between 2300-0600 LBT, and layovers that allow for workouts. Since that is harder to do on the bus, I'll retire off of this thing.

m3113n1a1

Once you deploy the reversers on a 737 RTO the speed brakes should deploy automatically, no need to arm them. If you forget or don't go into reverse, then yes you must do the speed brakes manually.

Nordhavn

Yes that sounds correct. If you don't deploy the TR's then no spoilers. My question is why Boeing or the operators don't arm spoilers for T.O. There is a reason why. The spoilers should really deploy full up as soon as you close the thrust levers. High speed aborts are dangerous and these spoilers are very important for performance.

2StgTurbine

Well then it's a good thing we train for these events. If I'm rejecting a takeoff: 1. Power idle, 2. Apply brakes/verify auto brakes, 3. Deploy the reversers, 4. Verify spoilers.

Boeings don't retract the speed brakes when you apply full power either. That's why we are trained to retract them during a terrain avoidance maneuver.

Would arming them before takeoff even work? I thought they only deploy once main gear touchdown occurs. I'm not sure if the logic would work if you are already on the ground.

Nordhavn

If doesn't matter if they're armed for T.O. or landing. The logic is the same. They work but for some reason Boeing has changed the procedure for whatever reason the systems book is a joke nowadays.

VforVendetta

Ummm, perhaps you should read the FM. You're doing it out of order. Always always speedbrakes first, then thrust reversers.it doesn't say "verify" it says "manually raise". The reason is that brakes do most of deceleration work. Reversers do a small part. It's much more important a d critical to deploy ground spoilers asap to exert more downward pressure onto the wheels so more force can be applied to the brakes before wheel locking (anti-skid system action). In fact there's zero credit given to stopping distance performance calculations on a dry runway, however Thrust Reverser performance is credited on a wet runway. That's how all the stopping performance calculations we use are calculated. With heavy emphasis on brakes + speedbrakes use, mush higher priority than thrust reversers.

FAR part 25 (Transport Category Aircraft) design criteria rules. This is where you look to see why the manufacturer designed systems in a particular way. The FAA mandates it that way. Its not boeing or airbus genius as much.

Here is a link to FAR 25.109 (accelerate-stop distance regulation criteria) its all in there.

https://www.law.cornell.edu/cfr/text/14/25.109


Here's a copy & paste from the FM: look at the priority of actions. Do it right please.

Captain
Accomplishes the following:
Calls “Reject” or “Reject, I have the aircraft”
Simultaneously brings both thrust levers to idle and disengages the autothrottles
Confirms RTO braking or initiates maximum manual braking
Manually raises speed brake lever
Initiates maximum reverse thrust consistent with runway and airplane conditions
Calls for the “Rejected Takeoff checklist”

I think I'm done here. This is getting too embarrassing.

VforVendetta

Ummm, perhaps you should read the FM. You're doing it out of order. Always always speedbrakes first, then thrust reversers. It doesn't say "verify" it says "manually raise". The reason is that brakes do most of deceleration work. Reversers do a small part. It's much more important and critical to deploy ground spoilers asap to exert more downward pressure onto the wheels so more force can be applied to the brakes before wheel locking (anti-skid system action). In fact there's zero thrustreverse credit given to stopping distance performance calculations on a dry runway, however Thrust Reverser performance is credited on a wet runway. That's how all the stopping performance calculations we use are calculated. With heavy emphasis on brakes + speedbrakes use, mush higher priority than thrust reversers.

FAR part 25 (Transport Category Aircraft) design criteria rules. This is where you look to see why the manufacturer designed systems in a particular way. The FAA mandates it that way. Its not boeing or airbus genius that much.

Here is a link to FAR 25.109 (accelerate-stop distance regulation criteria) its all in there.

https://www.law.cornell.edu/cfr/text/14/25.109


Here's a copy & paste from the FM: look at the priority of actions. Do it right please.

Captain
Accomplishes the following:
Calls “Reject” or “Reject, I have the aircraft”
Simultaneously brings both thrust levers to idle and disengages the autothrottles
Confirms RTO braking or initiates maximum manual braking
Manually raises speed brake lever
Initiates maximum reverse thrust consistent with runway and airplane conditions
Calls for the “Rejected Takeoff checklist”

I think I'm done here. This is getting too embarrassing.

2StgTurbine

We work for different companies. That's the order Delta does it.