AOG?
[Sorry for the bad pun.] Quote from Check Airman:
I entirely agree that the plane could have been "smarter" so that it could sense that it was on the ground (pilot applying brakes, selecting reversers, nosewheel weight etc...), but I wonder if a Boeing would be any smarter? In either event, I'm not trying to start an Airbus/Boeing debate. Remember that with each added level of complexity to the air/ground sensing, there's something else to go wrong.
I wonder what people think of having a reverser override, or air/ground override switch? It would obviously have to be guarded, but I think it may have saved the day (if not the tires) in Quito.
[Unquote]
Bring the Boeing/Airbus debate on, I say. Let you operational people (and even us ROFs) call both the megaplane companies to account. But let's leave out rhetoric and stereotyping, please, not to mention cheap jibes. Many of us have earned our crusts flying products from both sides of the pond. We might knock some sense into both of them... Actually, I won't be surprised if there's little difference in their ground/flight sensing, and how it affects this incident.
A guarded and wire-locked ground/flight switch would be difficult to reach and select on a bumpy runway. It took them 5 seconds after touchdown to recognise that autobrake had not kicked in on schedule, and to apply the brakes manually. A switch would take much longer.
In those circumstances, waiting for the IAS to reduce from 150 to 120 kts would use a lot of runway, and, when it became available, its deceleration force would already be lower than at (say) IAS 145. Fan reverse is not very effective anyway (but at least you're not getting forward thrust).
Quote from Mad (Flt) Scientist:
The existing systems for determining the "on ground" state are intentionally complex in order to minimise the risk of inadvertent in-air deployment, even in the event of (possibly dormant) system failures. The hazard associated with in-air deployment is, for most types, severe. The hazard of failure to deploy on-ground is IN GENERAL small - because normal planning factors have sufficient margin to account for failure (or non-use) of reversers.
[Unquote]
True. The three things missing were autobrake, reverser capability, and ground-idle. Ground-spoilers deployed, because the main-wheel spin-up sensors worked (luckily). Can someone remind us why main-wheel spin-up triggers ground spoilers, but is not used to enable reverser selection?
If any relaxation is warranted, perhaps it could involve vertical g and alpha. Once the nose is down, let's assume alpha stabilises at about zero (not like the B707...). In normal flight, wings level, this would inevitably involve a dramatic fall in vertical g from 1 towards 0. [Like the vomit-comet.] This wouldn't happen on the ground. Bumps could be averaged out, and humps do not drop the g that much.
Airbus might also consider using the existing nose-gear weight switches, which I don't think are used for this purpose. But the pilot would initially have to use forward stick to ensure the nose gear remained firmly on the ground, and might this reduce the effectiveness of the (main-gear) brakes on a wet runway?