Photo: from Haskel's jet
Approach categories seem to cause a lot of confusion in the corporate pilot world for some reason. The rules are pretty simple and are linked below. The confusion in the Gulfstream world was caused by magical two-sided plastic placards in the cockpit which pilots used to move at will from one category to another. The FAA ended all that with an emphatic statement that pilots could not do that, in fact only mechanics could do it with log book write ups. (The placards now only have one side, they are either installed or they aren't.)
In the G450, if you have ASC 007C installed, you are a Category C aircraft with a 58,500 lb landing weight limit, otherwise you are Category D with a 66,000 lb landing weight limit. Making the switch is more complicated than many of us in the Gulfstream world once thought.
Here then is a summary of the issue as it relates to the G450 and how to move from one category to another, and from one landing weight limitation to another.
|Max Landing Weight||Category|
More on this in the Normal Procedures & Techniques / Approach Categories section.
The G-V and G550 are almost always Category C aircraft since they circle at VREF+5 with 39° flaps and that speed is almost always below 141 knots. (You would have to be close to max landing weight and well above sea level to exceed 141 knots.)
The G-IV is almost always Category D aircraft since it circles at VREF+10 with 39° flaps and that speed is almost always above 141 knots. (You would have to weigh less than 50,000 lbs, less than 6,000 lbs of payload, to get under 141 knots.)
The G450 is better off since it circles at VREF+5 with 39° flaps and weighs a little less than a G-IV, but it still sometimes ends up above 141 knots. ASC 007 reduces the aircraft's maximum landing weight, thereby reducing the aircraft's approach category, as detailed below.
Remember, the pilot can always raise the category. (More on this: Normal Procedures & Techniques / Circling Approaches.)
And about moving back to Category D:
Bottom Line? If you have ASC 007C installed, you are flying a Category C airplane with a 58,500 landing limit. You can change either of those facts thusly:
14 CFR 97, Title 14: Aeronautics and Space, Standard Instrument Procedures, Federal Aviation Administration, Department of Transportation
Gulfstream G450 Aircraft Service Change 007C, Maximum Landing Gross Weight, 58,500 pounds, Category C, Provisions, October 26, 2011
ICAO Doc 8168 - Aircraft Operations - Vol I - Flight Procedures, Procedures for Air Navigation Services, International Civil Aviation Organization, 2006