View Full Version : ICAO Approach Speed Limits Category C types.

23rd Feb 2003, 06:56
Jepps (Air Traffic Control) - Flight Procedures -page 201- DOC 8168, has a table called Aircraft Approach Category. This is an ICAO table that indicates a specified range of handling speeds for each category of aircraft to perform the manoeuvres specified.

For a B737 (Category C) the range of speeds for initial approach is 160/240 (knots).

Question: Does this mean that until passing the final approach fix/point - (typically the outer marker on an ILS), a minimum IAS of 160 knots must be held in order to conform with the handling speeds in the table? Is this lower speed a limit and if so, why?

The problem arises where Boeing recommend a final approach stabilisation altitude in IMC of 1000 ft above runway level. Assuming an approach speed of 125 knots, then if using the 160 knots limit until passing the FAF - typically 4 miles (1300ft agl) - there appears to be a situation where the aircraft has to lose 35 knots in 300 feet in order to be stabilised by 1000 ft agl.

Request comment.

23rd Feb 2003, 09:10
I've always regarded these quoted speeds to be maximum speeds rather than minimum speeds, i.e. max clean would be 240 down to approx. 210, At the OM it would be max 160, (sometimes requested by ATC), down to, say, 125kts.

In a heavy B744 freighter with a max landing weight of 302 tonnes the bug speed would be in the region of 157kts, speed at the OM would probably be not less than 180kts, we always advised ATC of our intended/requested speeds though, since we tended to be outside those published in the Jeppeson.

23rd Feb 2003, 19:00
This same question appeared a few weeks ago on this very forum. The speeds quoted are for the purpose of procedure design calculations, and the construction of obstacle assessment areas.

The aircraft approach category is based on Vat

Generally speaking, if you are slower than the speeds quoted there is no problem. The upper limit is more critical.

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