22 MRJT Cruise

Question 1

Optimum altitude?

Answer 1

The altitude of minimum fuel burn, this will increase throughout the flight.

Question 2

What causes the maximum flight altitude to be limited?

Answer 2

Flight at the optimum altitude may be impractical or impossible due to the onset of high speed buffet, insufficient excess thrust or a lower maximum certified altitude.

Question 3

Where can high speed buffet occur?

Answer 3

High-speed buffet can occur at speeds slower or faster than M_mo.

Question 4

Turbulanet air buffet when can it occur?

Answer 4

Buffet from turbulent airflow that has separated from the wing can occur at low and high speed, depending on the cause. High speed buffet onset depends on altitude, aircraft mass, CG position, and load factor.

Question 5

Effect of bank angle on the buffet onset speed?

Answer 5

Bank angle reduces the buffet onset speed. If your step climb involves turning, you may have to delay the climb to a higher altitude.

Question 6

Buffet margin as mass decreases?

Answer 6

Reducing mass increase the speed of buffet onset. As fuel is consumed, the BOB becomes less restrictive on your step climb.

Question 7

Buffet margin as you descend?

Answer 7

When the aeroplane descends, the margin between the high and low speed buffet progressively increases. This allows you to fly within a widening range of Mach numbers without encountering buffet.

Question 8

Where are performance gradents for en-route obsticales found?

Answer 8

CS-25.123 specifies gradients based on net performance for en route obstacle clearance. The margin by which the gross gradients reduce varies.

Question 9

Effect of engine failure on excessive thrust?

Answer 9

Question 10

For one engine inoperative, the gross gradients reduce margins are:

Answer 10

• 1.1% for two-engine aircraft.
• 1.4% for three-engine aircraft.
• 1.6% for four-engine aircraft.

Question 11

For two engines inoperative, the the gross gradients reduce margins are smaller, because it is much less likely that two engines will fail:

Answer 11

• 0.3% for three-engine aircraft.
• 0.5% for four-engine aircraft.

Question 12

Minimum obstacle clearance if your aeroplane can achieve a positive net gradient with one engine inoperative?

Answer 12

If your aeroplane can achieve a positive net gradient with one engine inoperative, then your minimum obstacle clearance is 1000 ft within 5 nm of your intended track (provided you have sufficient navigation accuracy).

Question 13

Minimum obstacle clearance if your aeroplane can’t achieve a positive net gradient with one engine inoperative?

Answer 13

If your aeroplane can’t climb with one engine inoperative, then your minimum obstacle clearance is 2000 ft within 5 nm of your intended track (provided you have sufficient navigation accuracy).

Question 14

Climb gradient margins if navigational accuracy cannot be guarenteed?

Answer 14

If the aeroplane’s navigational accuracy doesn’t meet the 95% containment requirement, then you must increase the margin either side of your intended track from 5 nm to 10 nm.

Question 15

After take off climb requriements?

Answer 15

The aeroplane must be able to have some climb performance (a positive gradient) by the time it reaches 1500 ft above the intended landing aerodrome.

Question 16

What is drift down?

Answer 16

Likely an AC will not be able to sustain level flight at altitude and you will have no option but to drift down to a highet where remaining engines can generate sufficient thrust/a positive rate of climb.

Question 17

The optimum drift down speed?

Answer 17

The optimum speed during drift-down is V_MD or LRC depending on the circumstances. The optimum drift-down speed reduces with a reduction in the aeroplane’s mass.

Question 18

When is the highest possible stabalising altitude attained in the drift down

Answer 18

Descending at V_MD

Question 19

Effect of engine failure on the drift down speed?

Answer 19

Following engine failure, the initial deceleration to drift-down speed means a brief period of no loss of altitude. Thereafter, any further deceleration causes a deterioration in the L/D ratio and thus an increased rate of descent.

Question 20

Factors effecting the drift down speed?

Answer 20

Several factors affect the net drift-down flight path:

• Altitude: at high altitude the descent gradient is steeper.
• Temperature: high temperature reduces thrust increasing the descent gradient.
• Wind: a headwind increases the descent gradient, a tailwind reduces it.

Question 21

How does cost index effect change flight speed?

Answer 21

Cost index 000 is max range speed, 1.32 Vmd for jet. (High staff / AC time costs)