ATPL (A)
Review Worksheets
032 PERFORMANCES
BY KDMN
2020
,I/ CLASS OF PERFORMANCES – REGULATION
CLASS OF PERFORMANCES JET TURBOPROP PISTON
M > 5700kg or Nb of pax seats ≥ 9 Class A Class A Class C
M < 5700 kg and Nb of pax seats < 9 Class A Class B Class B
REGULATION CLASS A PERFORMANCES CLASS B PERFORMANCES
Certification CS 25 CS 23
Operation EASA AIR OPS Class A performance EASS AIR OPS Class B performance
II / DEFINITIONS – CALCULATIONS
01 STALL SPEED
➔ VSR= Reference stall speed, it must not be lower than VS1g, used for Certification Specification CS 25.
➔ VS0= Stall speed in landing configuration, used for Certification Specification CS 23.
➔ VS1=Stall speed in other configuration than landing configuration, used for Certification Specification
CS 23.
02 DENSITY ALTITUDE
It is the pressure altitude PA corrected with temperature. It is used to determine a/c performance.
03 WIND CALCULATION
• Wh, speed = Wspeed x cos (α):
Wh= headwind
➔ If cos(α)>0 -> Headwind
α
W = total wind WC= Crosswind ➔ If cos(α)<0 -> Tailwnid
• Wc, speed= Wspeed x sin (α)
• Ground Speed GS = True AirSpeed + Head/Tail wind = TAS + Wh,speed
04 PRESSURE ALTITUDE PA
All performance charts are given with pressure altitude, ie according to 1013Hpa. 1Hpa = 30ft.
PA = Altitude + (1013 – QNH)x30.
Ex1: Aerodrome Altitude = 2000 ft, QNH = 993. Δ(HPa) = 1013 – 993 = 10. Δ(ft)= 300ft -> PA = 2000 + 300 =
2300ft.
Ex2: Aerodrome Altitude = 2000ft QNH = 1023. Δ(HPa) = 1013 – 1023 = -10. Δ(ft)= -300ft -> PA = 2000 - 300
= 1700ft.
To know if you have to add/subtract Δ(HPa), draw a schema knowing that pressure decreases with altitude.
PA = 2300ft 2000ft
QNH = 993
1013
, 05 Δ(ISA) COMPUTATION
• ISA = at sea level : 15°C, 1013 HPa, -2°C/1000ft.
Ex: If Zp = 5000 ft, OAT = 10°C, what is ΔISA ?
➔ Under ISA condition : T°CISA at 5000 ft = 15 – 2x5 = 5°C, but here, T°C = 10 °C, it is warmer
-> ΔISA=+5°C.
Review Worksheets
032 PERFORMANCES
BY KDMN
2020
,I/ CLASS OF PERFORMANCES – REGULATION
CLASS OF PERFORMANCES JET TURBOPROP PISTON
M > 5700kg or Nb of pax seats ≥ 9 Class A Class A Class C
M < 5700 kg and Nb of pax seats < 9 Class A Class B Class B
REGULATION CLASS A PERFORMANCES CLASS B PERFORMANCES
Certification CS 25 CS 23
Operation EASA AIR OPS Class A performance EASS AIR OPS Class B performance
II / DEFINITIONS – CALCULATIONS
01 STALL SPEED
➔ VSR= Reference stall speed, it must not be lower than VS1g, used for Certification Specification CS 25.
➔ VS0= Stall speed in landing configuration, used for Certification Specification CS 23.
➔ VS1=Stall speed in other configuration than landing configuration, used for Certification Specification
CS 23.
02 DENSITY ALTITUDE
It is the pressure altitude PA corrected with temperature. It is used to determine a/c performance.
03 WIND CALCULATION
• Wh, speed = Wspeed x cos (α):
Wh= headwind
➔ If cos(α)>0 -> Headwind
α
W = total wind WC= Crosswind ➔ If cos(α)<0 -> Tailwnid
• Wc, speed= Wspeed x sin (α)
• Ground Speed GS = True AirSpeed + Head/Tail wind = TAS + Wh,speed
04 PRESSURE ALTITUDE PA
All performance charts are given with pressure altitude, ie according to 1013Hpa. 1Hpa = 30ft.
PA = Altitude + (1013 – QNH)x30.
Ex1: Aerodrome Altitude = 2000 ft, QNH = 993. Δ(HPa) = 1013 – 993 = 10. Δ(ft)= 300ft -> PA = 2000 + 300 =
2300ft.
Ex2: Aerodrome Altitude = 2000ft QNH = 1023. Δ(HPa) = 1013 – 1023 = -10. Δ(ft)= -300ft -> PA = 2000 - 300
= 1700ft.
To know if you have to add/subtract Δ(HPa), draw a schema knowing that pressure decreases with altitude.
PA = 2300ft 2000ft
QNH = 993
1013
, 05 Δ(ISA) COMPUTATION
• ISA = at sea level : 15°C, 1013 HPa, -2°C/1000ft.
Ex: If Zp = 5000 ft, OAT = 10°C, what is ΔISA ?
➔ Under ISA condition : T°CISA at 5000 ft = 15 – 2x5 = 5°C, but here, T°C = 10 °C, it is warmer
-> ΔISA=+5°C.
