As a line pilot on the B738 based in Cape Town, South Africa, I thought I'd have a bash at things from 'the other side of the screen' as it were. I've tried other ATC sims in the past, but frankly the hideous text interactions have always put me off - speech recognition has also not been up to spec, plus I've always wanted to play in my own back yard, ie the airfields I normally fly to. Thankfully, the simple drag and drop type interface in GATC, as well as the global database makes this all possible. Wall-o-text to follow:
The simple tutorials give you the basics of the interface which are easy to grasp, but very little 'training' in how to be an ATC (more tutorials are available on the Aerosoft website and are apparently more comprehensive, so this isn't a knock against the product). There are however, quite a few simplifications of procedures; some examples are no altimeter setting changes, no Mach/IAS conversion (you essentially tell the aircraft what ground speed to fly it seems unlike RL), likewise you tell the aircraft what track to fly (they seem to compensate for wind drift for you, not always done IRL unless asked for). The pilots are also all vegetables (don't joke, most of us are at least one step up from that!) in that they will happily fly into each other, and possibly the ground too. As an example, my very first flight was ended almost immediately after I cleared somebody for take off, then told the aircraft following to line up. IRL, the crew in the 2nd aircraft would simply wait until there was space to line up behind the departing traffic, but nope, the scenario ended as they taxiied straight into the other aircraft, which had actually reached 40kts already so was well clear (there is no simulation of intersection departures). There is also no simulation of ACAS RA's or EGPWS terrain avoidance (IRL a crew will avoid terrain and other transponder equipped aircraft). Also, with a bit of a crosswind aircraft will be unable to land and will constantly go-around - IRL, operational and procedural constraints often dictate a less than optimal runway; crews will only refuse in an emergency, or if the crosswind is considered excessive (crew restrictions, aircraft crosswind limits). For example, I 'forced' the use of RWY01 in FACT, with a wind of 340@15 aircraft were unable to land - IRL, using RWY34 (a shorter runway) isn't often done.
Basically I was looking for a bit more intelligence from the aircraft, perhaps an unrealistic expectation (actually, given the poor progress of AI in games in general, definitely unrealistic). As it stands now, you're basically remote controlling some drones (the way of the future?) The other thing I'd like to see is being able to clear aircraft for a visual approach without such harsh angular restrictions (they must be basically on final to accept a visual in game, in which case what's the point of the visual? May as well use the ILS.) IRL, if I can see the field and certain other constraints are met, if I'm cleared for a visual I fly myself onto final and land, from any direction (right or left, as cleared). I'd also like to be able to give them the option of flying at whatever speed they would like - IRL, the aircrafts FMC and company policy would dictate some kind of 'econ' descent (and as mentioned earlier, there's no transition between Mach number and IAS) and that's what crew would like to fly at - which brings me to my next point. I would have really liked to see some kind of efficiency rating - as it stands there seems to be no penalty whatsoever (and conversely no reward) for doing anything efficiently. IRL, pilots would scream bloody murder (after the flight of course) if you just 'forgot' to clear them to land (as I just did with Air France, sorry guys). Likewise, companies would like direct routings in empty skies - currently, you can leave everybody on a long roundabout departure and it makes no difference. To counter this, I'd like some kind of 'fuel efficiency' rating, comparing my performance to the worst case (ie all departures/arrivals flown in their entirety, aircraft held up in their climbouts etc). Along the lines of Max fuel burn/time enroute until clear of the sector vs actual fuel burn/time in the airspace. Something like that.
Some nice points, which I've found you can't always take for granted, are realistic times for lining up and getting rolling, as well a plausible simulation of what we often struggle with - energy management on the approach, in other words the old 'I can go down or slow down, but not both at once' problem.
But I'm being picky. At it's core, GATC offers a taste of the practical business of safely routing aircraft into and out of a worldwide database of airfields, including real world SIDs/STARs which is great. The simplifications of procedures don't really get in the way of this IMHO. It works, it's fun (if you like ATCing) and it covers the basics quite neatly in an easy to use interface. All my gripes could really be summed up as 'aircraft AI', perhaps something that is a bit beyond the scope of this project to do properly. I can therefore recommend it, again, assuming you have an interest in the subject at hand of course.