Sadly I am not sure this will be such a rare event in future. A dramatic growth In air travel - especially low cost air travel. More punishing crew schedules with busy nights and all the risks of fatigue. An ever increasing drive towards automation and efficiency. Reduced training budgets. Pilots with less hands on experience who are at increased risk of getting startled by the unexpected.
We are seeing this across society. Increased sophistication and people trained to be reliant on the "system." And increasingly less well prepared to take over when the system fails.
Not saying it will be common. But I fear common enough that tracking is justified.
Wouldn't the local change in baro pressure in a major updraft or downdraft give false readings to the transponder instrumention- thus indicating a major change in altitude even in relatively level flight
An interesting question. What altitude would you like tracked? FL as per altimeter? GPS derived altitude (when available)? Both?
Imagine if we had both and there was a sudden substantial discrepancy. Imagine how useful it would be in a case when it was going to takie time to get the recorders (deep mid pcean).
As an aside, how often is GPS coverage sufficient to permit altitude to be calculated.