This article first appeared in Aviation Week's Ares weblog.

About the only speaker at a London conference on unmanned combat air vehicles (UCAVs) this week who was in favour of the US Army's plans to operate a massive fleet of armed Sky Warriors was General Atomics-ASI's Steve May. And so he should be: "The Army is now as large a customer for us as the Air Force," May said.

According to May, the Army is looking at acquiring as many as 45 complete Sky Warrior systems once full-rate production starts in 2011 -- each with 12 air vehicles, 540 UAVs in all. The Sky Warrior resembles the USAF MQ-1L Predator but is heavier and more powerful, routinely carrying eight Hellfire missiles.

The numbers caused some raised eyebrows among delegates, as did the Army's plans for dealing with the consequences of fielding so large a force. (Most delegate comments are off-the-record, because discussion during the conference was held under Chatham House rules.)

Aircrew training is proving a major challenge for the Air Force as it expands its own Predator fleet. Sustaining one Predator orbit takes four aircraft and 80 people, 50 of them deployed forward, says Col. Chris Chambliss, commander of the USAF's 432d Wing. The wing aims to convert 240 students in 2007, and has extended its tours (three years for pilots, four for sensor operators) to reduce the training load as the USAF expands from 19 to 21 total orbits -- well ahead of schedule -- and has accelerated the deployment of the MQ-9 Reaper.

The Army's answer is to adopt a new ground station, provide the Warrior with automated take-off and landing and assign non-pilots to fly the aircraft. Sky Warrior Block 0 aircraft -- pre-production versions -- will be operational in February 2008, flown by Army aviators. Later aircraft, though, will be flown by non-pilot warrant officers.

But as one Predator pilot observes, "we're flying to take part in exercises and we're allowed to be in civilian airspace, 1000 feet away from jumbo jets. Who's going to like a non-rated Army officer doing that?" Another operator says simply: "In order to apply lethal force you should be a rated aviator." Underlying this: a real concern that if the Army has got it wrong, a blue-on-blue disaster or a midair will set back the development of UAVs by decades.