## Requirement 4: Missed Approach Climb |

JAR 25.121 Climb: One-engine-inoperative.

(d) Discontinued Approach. In a configuration in which VS does not exceed 110% of the VS
for the related all-engines-operating landing configuration, the steady
gradient may not be less than

**2·1 %**
for two-engined aeroplanes,

**2·4 %** for
three-engined aeroplanes, and

**2·7 %** for four-
engined aeroplanes, with -

(1) The critical engine inoperative, the remaining engines at the
available take-off power or thrust;

(2) The maximum landing weight; and

(3) A climb speed established in connection with normal landing procedures,
but not exceeding 1·5 VS.

(4) Landing gear retracted.*

* Number (4) of § 25.121 (d) exists only in JAR 25 but not in FAR Part 25.

The missed approach is similar to the second segment situation where one engine of the aircraft is inoperative. The thrust of the remaining engine(s) has to be enough to climb again as required. The second segment climb equation is expanded by the mass ratio determined already in the landing field calculation:

The climb gradient can simplified similar to the second segment:

The lift coefficient is the landing lift coefficient divided by 1.69, because the climb speed is 1.3 times the stall speed.

The drag coefficient consists of five parts:

where the

- Oswald's airplane efficiency factor
**e**is 0.7, - wing aspect ratio
**A**is given or taken from statistics, - drag coefficient at zero lift
is assumed to be 0.02,*c*_{D, 0} - landing gear drag coefficient
is 0.015,*c*_{D, gear} - slat drag coefficient
is neglected and set to zero,*c*_{D, slat} - flap drag coefficient
:*c*_{D, flap}

for= 1.3 : flap deflection 15° =>*c*_{L}= 0.01*c*_{D, flap}

for= 1.5 : flap deflection 25° =>*c*_{L}= 0.02*c*_{D, flap}

for= 1.7 : flap deflection 35° =>*c*_{L}= 0.03 .*c*_{D, flap}

background of mass relation statistics of aspect ratio next: calculation of takeoff thrust to weight |

Figure 2: chart for calculated results

The takeoff thrust to weight ratio of the aircraft must be above the pink line to fulfil the requirement for the missed approach condition. (Bear in mind: Thrust means climb rate.)

Aircraft | Airbus A 300-600B | Airbus A 310-300 | Airbus A 340-300 | Antonov AN 124 | Boeing B 737-600 | Boeing B 777 | McDonnell Douglas MD11 | Tupolev TU 204 |
---|---|---|---|---|---|---|---|---|

Takeoff thrust Takeoff weight [ - ] |
0.308 - 0.324 | 0.290 - 0.356 | 0.220 - 0.240 | 0.231 | 0.307 | 0.292 - 0.304 | 0.299 - 0.309 | 0.341 - 0.413 |

save the result temporary (Set browser preferences to: "Accept cookies") next: matching chart back to the start page |