High Speed Turnoff Defintion
 

Each airplane has recommended speeds at which to exit the runway via a high speed turnoff.

What is the defintion of a high speed turnoff? Is there a specific length the turnoff must be to be considered high speed?

How can I identify on a JEPP plate whether a turn off is officially considered a high speed one?

In the old days we called them Rapid Exit Taxiway (RET).
"Rapid Exit Taxiway — A taxiway connected to a
runway at an acute angle and designed to allow
landing aeroplanes to turn off at higher speeds
than are achieved on other exit taxi-ways and
thereby minimizing runway occupancy times."
Page 21 http://ww1.jeppesen.com/documents/av...ry-legends.pdf

See http://www.gcmap.com/diagrams/pdf/EGLL.pdf
"HOLD N4W/RAPID EXIT TAXIWAY (RET) REDESIGNATED AS UNDER CONSTRUCTION." as an example of what one looks like.

See page 166 http://ww1.jeppesen.com/documents/av...port-signs.pdf

Lots of information on radius of turn / maximum speed etc here :icao_doc_9157_aerodrome design manual-part2.pdf

ICAO Annex 14 defines a RET as one that departs the runway at an angle of between 25° and 45° (ideally 30°) and is able to accommodate Code 3 or 4 aircraft exiting at a speed of up to 93 kph in wet conditions.

As for the length, Annex 14 simply states that "A rapid exit taxiway should include a straight distance after the turn-off curve sufficuent for an exiting aircraft to come to a full stop clear of any intersecting taxiway."

Is kph kilometres or knots?

A knot is a unit of speed, so knots per hour is actually an acceleration, like meters per second per second, so not a likely unit in this context.

km/h

Don't try it at 93kts

That's runway code rather than aircraft code

No idea why, but the grey cells seem to have an idea, from centuries ago, that 45 degrees & 45kts have some relevance.

Well yes and no. It describes the aerodrome, but in terms of the aircraft it's intended for. From Annex 14:

"The code is composed of two elements which are related to the aeroplane performance characteristics and dimensions. Element 1 is a number based on the aeroplane reference field length and Element 2 is a letter based on the aeroplane wingspan and the outer main gear wheel span".

My OMA states max 50kts for turn off , best to do it even slower, many at times it's a rapid and then a 90 degree turn after. Keep it slow.

Which of course is the same as the 93 km/h quoted by metricated ICAO.