Upload
elsa-hemple
View
226
Download
2
Embed Size (px)
Citation preview
CDOs – the flightdeck perspectiveCaptain Spencer Norton
AOA Environment Conference 28th April 2014
Why not all the time?• CDOs/CDAs are beneficial in terms of noise and fuel
efficiency
• Pilot needs to consider 3 things:
1. Height vs track miles
2. Speed reduction vs track miles
3. Rate of Descent vs track miles
Using our 3 times tableHeight vs track miles
8000ft x 3 = 24nm
7000ft x 3 = 21nm
6000ft x 3 = 18nm
5000ft x 3 = 15nm
4000ft x 3 = 12nm
Reducing our speedWe need to reduce our speed – we need distance to do this
1nm per 10 knots reduction of speed
For example:
To reduce from 250kts to 220kts
Δ 30kts
1x3 = 3nm required
Rate of Descent
Dependent on speed
A very ‘general’ rule of thumb:
1. Indicated speed – add a zero (220kts = 2200)
2. Divide this number by 2 (2200/2 = 1100fpm)
Example 2:
IAS = 160kts
1600/2 = 800fpm
Let’s put you in the hot-seat
Indicated Airspeed Altitude Groundspeed
Wind
Runway (EGPH 24)
Aircraft
Flight Management Computer
The ‘To’ Waypoint
Miles to go
You are inbound to EDI RWY 24, expecting no delay and have just taken up a radar heading from TARTN.
ATC have given you no indication of expected track miles to run. The CI24 point is at 10nm on the ILS for 24.
Speed = 250kts Altitude = 9000ft Miles to go = 30nm
Are we?
HIGH
ON PROFILE
LOW
PLAY YOUR CARDS RIGHT
Are we?
HIGH
ON PROFILE
LOW
PLAY YOUR CARDS RIGHT
This also agrees with the ‘raw data’ calculation of track miles required.
Height AAL 9000’ x 3 = 27
Decel to 220kts (1nm/10kts) 3 x 1 = 3 30 nm
This is actually one of the ‘gates’ we aim for.
Speed = 250kts Altitude = 9000ft Miles to go = 30nm
How are we doing now?
Looks similar to our first example, doesn’t it?
Are we?
HIGH
ON PROFILE
LOW
PLAY YOUR CARDS RIGHT
Are we?
HIGH
ON PROFILE
LOW
PLAY YOUR CARDS RIGHT
Spot the tail-wind!Any head/tail-wind must be accounted for in our calculations:
Height AAL 9000’ x 3 = 27Decel to 220kts 3 x 1 = 3Head/Tail wind (1nm/10kts) 3 x 1 = 3
33nm now required
Conclusion
• CDO approaches are beneficial in terms of noise and efficiency
• CDOs require thought – advise crews they are required!
Conclusion
Conclusion• CDO approaches are beneficial in terms of noise and efficiency
• CDOs require thought – Advise crews they are required
• Essential components to fly a CDO
1. Accurate track miles from ATC
2. Speed reduction to be considered
3. Correct rate of descent used
4. Wind conditions to be considered
Beyond the Flight Deck