As you may have heard, London's Heathrow Airport is so congested, arriving planes are regularly kept in a circling 'holding pattern' over the Home Counties. This, we are reassured, is normal. Nothing to worry about, as Croydon passes beneath you for the umpteenth time, and several other planes circle above you like frustrated drivers looking for a supermarket car park space on a Saturday morning.
But if, in the tedium of waiting for air traffic control to grant a landing slot, the pilot and co-pilot up front haven't nodded off? As unlikely as that might be, the chances of your pilot and even co-pilot being asleep at the joystick are alarmingly high.
The British airline pilots' association, BALPA, recently reported that 43% of its members have reported falling asleep during a flight and, worse, three-quarters have come awake to find their co-pilot zonked out next to them.
"A pilot falls asleep on the flight deck on a UK-registered airplane at least once in every 24 hours - and probably a lot more than that," according to Dr Rob Hunter, BALPA's head of flight safety.
Fingers inevitably point towards overworked flight crews as the airline industry maintains its relentless expansion on the back of the low-cost boom of the last two decades. While it has allowed more of us to visit more places more often than at any time in the history of leisure travel, the pilots taking us there are being stretched even further.
The airspace they are flying in is increasingly congested, their flying rosters ever-more overloaded, and the economic pressure on their employers' profit margins, even heavier as they manage to balance their engorged turnover with higher fuel costs and taxation.
It is not surprising, then, to learn of incidents such as that in 2011 of a captain returning from a toilet break who was unable to re-enter the heavily secured (post-9/11) flight deck because his co-pilot was unconscious. Disaster over London was avoided when the pilot used an emergency code to open the cockpit door.
BALPA says the severity of the problem is being masked by pilot reluctance to report such incidents, especially given the two-year jail sentence they would face if prosecuted. However, the situation won't be getting any better, anytime soon.
A proposed change in European law could see pilots asked to work even longer hours, more often, and more regularly overnight. EASA - the European Aviation Safety Agency - is widely expected this year to agree new limits on how long a pilot can work, relaxing current restrictions on night flying from 10 to 11 hours.
Worse still is the way the body reacts at night. As anyone familiar with shift work or insomnia will understand, at around 4am the body is at its drowsiest, as this is the time of night when the body is normally - or should be - at the deepest part of its sleep cycle.
Pilots flying longhaul routes are required to take regular sleep breaks, but for those flying shorthaul routes in Europe this has never been an issue, seeing as few passenger aircraft undertake nighttime operations. However, this does not take into account 'saddle time' - the number of consecutive hours a pilot clocks up in a day's work since leaving the comfort of bed.
Property prices, low salaries and the repayment of training fees have led to many younger, less experience pilots in the UK having to live further away from their base airports, requiring even longer commuter journeys before they've even looked at a weather map.
Britain's Civil Aviation Authority, for its part, rejects any claims from the pilots' association about safety: "We have no evidence of significant safety concerns with regard to crew and fatigue," says a spokesperson. But the increasing incidence of potentially dangerous "events" where tiredness may have been a factor points to a different reality.
One of the reasons air travel became popular in the first place is that it took the 'you' out of the equation of travelling long distances. It's a fairly safe bet that if you knew your plane had no pilot, and was being flown by nothing more than a souped-up PC, you wouldn't get on board (let's face it, "THIS APPLICATION HAS UNEXPECTEDLY QUIT" is not something you'd want to appear on the control panel of a passenger plane).
Technically, however, a commercial plane can fly itself, and for the most part it does. Much of any journey is carried out by autopilot (the non-inflatable kind), with the airplane programmed to follow strict air routes. Take-offs and landings are even governed, to a certain degree, by automated systems. But although passengers have just about accepted using driverless monorail carriages to get to and from airport terminals, a pilotless airliner is a Rubicon the airline industry is not yet prepared to cross.
And yet, as the military increasingly looks to pilotless aircraft as the future of fighting wars without anyone you actually like getting hurt, surely it won't be long before someone in the airline industry - and God knows Ryanair must be giving it full consideration - replace Mr. & Mrs. Chuck Yeager up front with a geek in a darkened room in Crawley with a glorified PlayStation controller.
It's a sobering thought as you strap yourself in for two weeks of burnt flesh and hangovers on the Costa del Sol.