Pretty good if they use frangible ammo.
http://www.globalsecurity.org/military/systems/munitions/frangible.htm
Frangible Ammunition
Frangible, or “soft,” rounds are designed to break apart when they hit walls or other hard surfaces to prevent ricochets during close-quarters combat. Frangible ammunition represents the first viable revolutionary change to firearms science in the past 100 years.
Frangible ammunition is a relatively recent development in bullets, presenting a departure from the standard projectiles in use for both range shooting and personal protection.
With the advent of modern hostage rescue tactics in the 1970s and 1980s, the military and police agencies began to look for ways to minimize overpenetration risks. One widely-accepted solution was the frangible round, also known as the AET (Advanced Energy Transfer) round.
Frangible rounds are available in a wide array of pistol calibers, but due to the inherently high velocities of rifle rounds, frangible ammunition is much less effective in rifles.
It is only produced in 5.56mm NATO and 7.62mm NATO, and its performance in actual combat is dubious. There are two frangible rounds that have been approved for training purposes only.
One is a 9mm, and the other a 5.56. Approval for operational use will depend on the special mission requirements (the military necessity) for the round.
Frangible bullets are not made from a lead projectile covered with a copper jacket, but are composites of hybrid materials either pressed together at high pressure or glued together with adhesives.
Frangible bullets are designed to break up into smaller pieces upon contact with harder objects or surfaces. The polymer-compound round produces no splashback and vastly decreased ricochets.
So, you are suggesting that, although allowing any firearm is fine, the FTA guys should make sure that all the bullets brought onboard are FRANGIBLE??? Do you happen to see how easily circumvented that would be?