Managing Your Speed Below 10,000 ft. – Jets
Here are a few tips to help keep your speed from exceeding 250kts while operating the jet fleet at or below 10,000 ft. The tips are segmented into departure and arrival procedures.
Departure (We recommend that you make these steps the last ones before gate departure)
- First, dial the speed you want to hold (250kts) into the flight management system.
- If you are flying the B773 or any of the A3xx jets the next step is to arm the auto-throttle system.
- If you are flying the E170, Legacy or CRJ7 aircraft, do nothing else to the navigation system after setting the target speed.
Note: The auto-throttle and speed hold are activated by two separate switches in the B773 and A3xx jets. In the E170, Legacy and CRJ7 both systems are tied to one switch.
- Taxi out and prepare for takeoff.
- Passing through 300 ft AGL engage the speed hold.
Passing through 10,000 ft. you may increase the target speed as desired but within operation limits of the aircraft.
- Descending through 13,000 ft, set your target speed to 240 kts. (Pay closer attention to your rate of descent at this point. You may need to decrease it to aid speed bleed off.)
- If by 11,000 ft the aircraft isn’t at or close to 250 kts, you may use spoilers to slow the aircraft.
Note on using spoilers: Spoilers add a sudden and huge amount of drag. The auto-throttle system will cause the aircraft to speed up once within 20 kts of the target speed with spoilers deployed. To illustrate: You are currently doing 290 kts and you want to slow down to 230 kts, so you set 230 as your target speed. If you extend spoilers, once the aircraft gets to 250 kts the auto-throttle will cause the aircraft to start speeding up, and if the spoilers are not retracted the aircraft will maintain a speed much greater than what is set. In effect the auto-throttle system is trying to compensate for the significant amount of drag introduced when the spoilers are extended. A method you could use if you have to deploy spoilers is this:
- Set throttle levers to idle.
- Disengage the auto-throttle system completely in the reverse order of engaging it – disengage speed hold then turn off the auto-throttle switch.
- Deploy spoilers and allow the aircraft to slow down to 15 kts below target speed.
- Retract spoilers.
- Enable auto-throttle. Then engage speed hold.
Additional note: If you’re using FSX, be careful how you disengage and engage the auto-throttle system on the B773 while in-flight. The flight management system on this aircraft is very sophisticated and if not employed properly, could yield some very surprising results.
There are no comments on this entry.
There are no trackbacks on this entry.