How annoyed do people get over air security?
The chairman of British Airways has complained about US-driven air security measures, but how annoyed do American passengers get over the issue?
Any regular air traveller is accustomed to long queues to go through security.
And when any journey goes through the US - with standards ever more stringent in the years since 9/11 - many people expect that security to be more onerous.
A series of threats has led to many passengers being asked to remove shoes before passing through the airport metal detector, as well as the restrictions on taking liquids in hand baggage. Passengers are also required to remove laptops from laptop bags before scanning, a requirement that puzzles many.
But BA chairman Martin Broughton complains that the way rules are applied on domestic US flights can differ from international flights.
"America does not do internally a lot of the things they demand that we do," Mr Broughton told the Financial Times. "We shouldn't stand for that."
Annoyance with differing security standards is a sentiment that passengers' groups also regularly hear.
"Inconsistency. That's the reason it becomes annoying," says Michael Cintron, director of consumer and travel industry affairs at the Dallas-based International Airline Passengers Association.
"The length of the wait in the queue, the annoyance of having to take off your shoes in one location but not another."
The US's Transportation Security Administration advice to passengers seems unequivocal.
"Travellers are required to remove their shoes before entering the walk-through metal detector at all US airports and put them through the x-ray machine for inspection," the advice says.
The procedure is primarily the result of Richard Reid's attempt to bomb an airliner with explosives hidden in his shoes.
But it is not applied rigorously at all US airports, notes Chris Yates, air security analyst at Jane's Information Group.
"A lot of measures have been put in place," he says. "There are still different standards about what is applied internally."
Part of the problem is a raft of different regulations exist, he notes. There is the International Civil Aviation Organization which applies a basic global standard, there are the rules from the Department of Homeland Security in the US, and the EU has its own rules.
"We should have one set of gold-standard rules that apply equally everywhere," Mr Yates suggests.
The inconsistency over shoes, Mr Yates explains, can be because even a single single airport can apply different standards at different times according to threat information.
There is no doubt that passing through airport security these days can be a very stressful experience for many.
"You have some very extreme views - [Some people ask] 'how come you are not selecting the right people for the security and screening and inconveniencing the rest of us'," adds Mr Cintron.
But while there may be anger over the confusing application of the rules, surveys suggest that many air passengers are very accepting over security measures.
A survey done for the Unisys Security Index found 93% of Americans said they were willing to sacrifice some level of privacy to increase safety when flying.
And to take just one controversial measure, full body "naked" scanning, nearly two-thirds were happy to undergo it. In the UK, there was even more acceptance at 90%, the highest of any nation.
Not everybody can accept it of course. A pilot wearing uniform who refused to pass through a full body scan while on his way to work is pursuing a complaint against the TSA. Michael Roberts's case has been taken up by civil rights group the Rutherford Institute.
The top causes of annoyance to passengers are not related to security, suggests Mr Cintron.
Poor service and hidden fees dominate the stream of complaints, he says. People get more annoyed about mystery delays and complex baggage fees. One US airline - Spirit - even charges for carry-on bags.
Some of the annoyance on the security front may be dissipated by technology.
The issue of laptops for instance, could be resolved by research currently being conducted in Canada, Mr Yates says.