Weekly tips, technique and training from IFR.

Features March 2014 Issue

What’s a Sim Good For?

A Rose, By Any other Name...

The question always comes up: What’s the difference between a Level B and a Level D sim? What about PC-ATDs? What category is that old ATC-50 gathering dust at the flight school?

The best answer is: You don’t care. What matters is the training value each offers.

The longer answer is that Level A-D (what I call “true sims”) are differentiated across 90 pages of a 300+ page document, plus half a dozen Advisory Circulars. For example, all four must have, “Visibility and RVR measured in terms of distance. Visibility/RVR checked at 2,000 ft (600 m) above the airport and at two heights below 2000 ft with at least 500 ft of separation between the measurements.” But only C and D must show, “Patchy fog giving the effect of variable RVR,” and only D must show, “The simulation of runway contaminants must be correlated with the displayed runway surface and lighting where applicable.”

See where this is going? Oh, and helicopters get their own tome and their own levels B-D. So, what you can do is spelled out in the letter of authorization for the physical simulator you’re flying. Ask the school. If you like wading through minutia, you can visit the National Simulator Program and get the actual docs (

Training devices are similarly broken up into Flight Training Devices (FTDs) levels 4-6 (4-7 for helos) and Aviation Training Devices (ATDs) that are either Basic or Advanced. Airplane FTDs get about 50 pages of stats to define them.
Currency logging differs little on the training devices, but logging for ratings does. The authority on how much of what can be logged on a device comes from the device’s FAA authorization letter. ATDs can use a generic letter in some cases. FTDs all get a specific approval letter that must be renewed.
What happened to FTD Levels 1-3, not to mention PC-ATDs? The FAA changed its mind trying completely unsuccessfully to keep up with changing technology. Once-approved items are grandfathered in, however, so a PC-ATD that was blessed by the FAA back in the day can still be used for 10 hours towards an instrument rating—just as a more advanced B-ATD that has all the real switches, avionics and visuals or that vintage ATC-50 that resembles a Heathkit project advertised in a 1963 Popular Science.
Go figure.

And, as I write this, FAA legal is threatening to change it again, sunsetting all authorization letters on GA sims, requiring new ones. This would hit all the grandfathered-in systems and ATDs hardest. So even this sidebar is “subject to change.” —JVW

Next: Cool Tools for GA Sims

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