What happens if a pilot dies mid-flight?
There are two pilots in a cockpit for a reason.
The death on Monday of an American Airlines pilot flying an A320 with 147 passengers on board between Phoenix and Boston was not a story that the surging numbers of air travellers worldwide would like to see on their in-flight entertainment streaming devices.
Especially in America, where the in-flight news feeds are often live.
But despite the tabloid panic impact of the news, this was only the seventh pilot fatality during a scheduled commercial flight since 1994 in US skies, according to the Federal Aviation Administration, although it came barely a day before a United first officer flying a 787 from Houston to San Francisco collapsed at its controls around the time the plane reached cruising altitude at 40,000 feet.
Both flights were safely landed at the nearest suitable airport by the remaining pilots, who are trained to fly aircraft single-handedly in such a crisis.
For airlines, pilot deaths and incapacitations are treated in the same way, and the most recent US study to hand, 10 years ago, found there had been 50 pilot incapacitations, including deaths, over a five-year period, all of them without causing injury to any other person.
This training is integral to being an airline pilot anywhere on the planet scheduled turbo-prop and jet services are flown, which is important, as passenger numbers worldwide have more than doubled since that last available US study on pilot incapacitations.
In modern times there are no records of pilots dying at the controls of a scheduled passenger flight in Australia. However, the records attribute the fatal crash of a TAA DC-4 freighter on approach to Brisbane airport in 1961 to the captain having a heart attack and falling over the controls while attempting to leave his seat.
Thanks in a tragic way to the Germanwings pilot suicide and mass murder crash in France in March, Australia has moved into line with most other countries in requiring that one pilot or cabin crew has to remain in a cockpit when the other pilot is out of it.
Pilots are only permitted to take leave of the cockpit for any reason during cruise, when a flight is routinely being managed with the assistance of an auto-pilot. The absent pilot is expected to return promptly even though the security door is locked from within, although in many instances, more than two pilots may be in the cockpit anyhow. This is particularly likely if it is a long-range international flight, where duty hours rules and other procedures involve the rotation of pilots through the "office".
The focus during a pilot incapacitation is on control of the airliner and an immediate landing. The cockpits of smaller airliners are tight, and assisting a stricken pilot from a seat so that he or she can be dragged back into the cabin for medical assistance is always problematical, especially if a suitable airport for an emergency landing is close at hand, requiring the full attention of the other pilot -- who might be about to fly an approach to the landing place for the first time.
If the last International Air Transport Association figures (for 2013) are extrapolated for known rates of growth, there are about 9.6 million people in the air for part of any given day on between 60,000 and 70,000 scheduled flights in airliners carrying on average of just over 135 passengers.
Hundreds of these people may have cardiac events or serious health crises at the airports, and dozens of them will fall ill during their flights, some of them ending in their deaths.
Although there are no stats at hand, airlines are known to routinely screen and reject pilots from rostering on duty each day because they check in for duty unwell, or self-monitor their well-being and advise their companies of their being unfit to fly on the day.
These are additional processes that reduce the risk of pilot incapacitation and have been in integral self-checking or self-filtering process for airline operations since before the jet age began.
Current reporting through industry sites, notably the Aviation Herald, also flag pilot incapacitations occurring worldwide at a rate of at least one a week.
In addition to the two US incidents so far this week, a British Airways 777-200 aborted a flight from London to Tel Aviv last week when the first officer became incapable of continuing his duties as the jet was climbing past Brussels. The jet returned to Heathrow.