Takeoff speed (TOS)
The speed at which the main gear lifts off the runway
Single engine takeoff speed (SETOS)
The speed at which the aircraft is able to climb, out of ground effect, at a minimum of 100’/min with gear down and flaps 60%
Assumptions:
- accelerate in a 3 point attitude to SETOS
- rotate no earlier than SETOS
- delaying rotation improves performance (8-50FPM for every knot above SETOS)
- best RoC with gear and flap is 200KCAS at 12,800 (add/subtract 8 knots for each 1000 lbs)
- for WSSP, include weight in total weight to compute SETOS, then add 1 knot
Takeoff distance (TOD)
TOD is the distance in feet from brake released to main gear liftoff
Assumptions:
- rolling TO increases TOD by a few hundred feet
- ground roll increases 3% for each % of uphill gradient
- for WSSP, add weight to total to calculate TOD, then increase by 1%
Normal acceleration check speed (NACS)
NACS is the speed an average T-38C should reach at a specified check distance
Assumptions:
- if NACS > CEFS, NACS will be moved to a usable point (usually 500’)
Min acceleration check speed (MACS)
MACS is the minimum acceptable speed at the check distance with which takeoff should be continued
Assumptions:
- less than MACS invalidated all TOLD
- calculated by subtracting 3 knots from NACS for every thousand feet difference between runway length and critical field length
Refusal speed (RS)
The maximum speed to which the aircraft is able to accelerate with both engines operating in MAX, and either: abort with BEO or abort with EF
Assumptions:
- assumes 3s reaction
- cautious braking 130-100, optimum braking beyond 100KCAS
- no aero brake
- add 50% of headwind to RS
- subtract 70% of tailwind from RS
- for icy runway, subtract 5 knots / 10 knots of tailwind
- with anti ice (BEO): no change for non-aero brake, -2 knots for with aero brake
- anti ice (EF): -2 no aero brake, -4 with
Decision speed (DS)
Min speed at which the aircraft is able to experience an instantaneous engine failure and still accelerate to SETOS and takeoff (approx 700’ from start of rotation) in the remaining runway
Assumptions:
- 3 second delay for reaction time
- if aircraft rotated at end of 3s, the ac is returned to 3-point attitude and accelerated (MAX) to SETOS
- smooth rotation at SETOS until takeoff occurs
Critical engine failure speed (CEFS) and critical field length (CFL)
The speed at which an aircraft can accelerate with both engines, lose an engine, and permit acceleration to SETOS and takeoff (700’ from rotation) or deceleration to a stop in the same distance. That distance is CFL
Assumptions:
- increase or decrease CEFS by 3 knots / % of gradient
- increase CFL 4% or decrease 3% per % gradient
- include weight of WSSP
- CEFS and CFL are valid up to SETOS
Landing distance (LD)
The distance required after main gear touchdown to slow the aircraft from landing speed to a safe taxi speed using normal braking
Assumptions:
- 100% flaps
- 7.5deg aero brake
- desired braking within 2s of nose gear touchdown
- cautious, then optimum braking
- 5% deviation above computed landing speed can increase rollout by 10%
