[Ol' Dan Tucker]

But to try to balance a gun on your lap and padlock it while flying an airplane 300 miles an hour, sometimes in the dark, is not secure," Mr. Mackett said....

Most airliners have two pilots in the cockpit.

What was the other one doing while all this was going on?

The armed guy couldn't simply say to the other guy, 'Hey, can you take the controls whilst I lock up my pistol?'

Most airliners also have map lights in the cockpit so the pilots can read their maps at night.

[TalonDJ]

The armed guy couldn't simply say to the other guy, 'Hey, can you take the controls whilst I lock up my pistol?'

Most airliners also have map lights in the cockpit so the pilots can read their maps at night.

Those lights are not all that bright.
There is still stuff going on in the cockpit to distract him even if his hands are not on the controls.

You should never handle a gun if there is not a 'safe direction' you can point it in, regardless of lighting and distractions. In the cockpit of an aircraft there is no safe direction.