Pilots and air marshals are reporting Arab men are testing airplane security.  It’s happening frequently.

Pilots and air marshals who asked to remain anonymous told The Washington Times that surveillance by terrorists is rampant, using different probing methods.
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A January FBI memo says suicide terrorists are plotting to hijack trans-Atlantic planes by smuggling “ready-to-build” bomb kits past airport security, and later assembling the explosives in aircraft bathrooms.
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A second pilot said that, on one of his recent flights, an air marshal forced his way into the lavatory at the front of his plane after a man of Middle Eastern descent locked himself in for a long period. 

The marshal found the mirror had been removed and the man was attempting to break through the wall. The cockpit was on the other side.

The second pilot said terrorists are “absolutely” testing security.
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“It’s a probe. They are probing us,” said a second air marshal, who confirmed that Middle Eastern men try to flush out marshals by rushing the cockpit and stopping suddenly.

We don’t have enough air marshals to put on all the flights.  Not nearly enough.  And these arab teams are have been composed of six to fourteen people.  That might be enough, with the right tatics, to neutralize the air marshals even if they were on the flight.  If you fly be prepared to defend the plane because the government can only do a very limited amount to protect you.  And remember the governments back up plan — F-16s.