Optimise your Descent

Thee FAA has ‘stepped up’ their game in reducing emissions and save fuel by reducing the number of ‘step down’ approaches into some major airports.

Here is a mini ‘what you need to know’ about CDAs, OPDs and how and where to fly them.

What’s the difference?

Seems a good question to answer first.

There are generally three types of descent you can expect when you head into a big, controlled airport.

The Step Down
A CDA
An OPD

The Step Down is exactly what it sounds like – you descend, level off, maintain that for a bit, then descend again, level off again, maintain it for a bit again…

This generally sucks for three reasons. One it is annoying for pilots because it means you have to do more. Two it can be a lot noisier on the ground if airplanes are roaring along low level, at lower speeds and three it is obviously a lot less fuel efficient.

Next up, you have the CDA – the constant descent approach. Again, exactly what it sounds like. (I feel like I don’t really need to explain this to pilots reading this but who knows, maybe a non-pilot has taken a random interest in it because of the excellent picture I used for the header).

So, with a CDA ATC, or the pilot, attempts to continue descending without levelling off. This is better for the reasons already stated above, but it is not the best because a CDA can mean descending with thrust on. A good example is EGLL/London Heathrow who still consider it a CDA if you’ve descend more than 50 feet in 2nm, and don’t have a level segment of more than 2.5nm below 6000′.

Which brings us to the OPD.

This acronym stands for ‘optimised profile descent’. Sorry, optimized (because its an American name so I’ll give it the ‘z’).

Not to be confused with ODP (Obstacle Departure Procedures). I feel like we may have reached a point in aviation where every acronym possible has been used.

Anyway, the ODP tries to have the aircraft descend with close to idle thrust, meaning they will be at a more fuel efficient altitude for longer, and descend in the most fuel efficient way.

If you’re still confused, then the FAA made this video explaining it, and I made this excellent visual representation of it below.

Completely pointless descent diagram

Where in the USA are these happening?

There are 11 airports that have had OPDs implemented recently:

KBCT/Boca Raton Airport
KFXE/Fort Lauderdale Executive Airport
KMCI/Kansas City International Airport
North Palm Beach County General Aviation Airport (F45)
KOMA/Eppley Air Field, Nebraska
KOFF/Offutt Air Force Base, Nebraska
KMCO/Orlando International Airport
KLNA/Palm Beach County Park Airport
KPBI/Palm Beach International Airport
KPMP/Pompano Beach Airpark
KRNO/Reno Tahoe International Airport

But wait! These are not the only ones. There are in fact others which got them in 2021:

KDFW/Dallas-Ft. Worth International Airport
KFLL/Fort. Lauderdale-Hollywood International Airport
KLAS/Harry Reid International Airport
KNEL/Lakehurst Maxfield Field
KDAL/Dallas Love Field
KMIA/Miami International Airport
KVGT/North Las Vegas Airport
KMCO/Orlando International Airport
KCMH/Port Columbus International Airport
KPDX/Portland International Jetport
Numerous other mid-size airports

There might even be more. This isn’t really a new thing and any US based folk reading this are probably thinking “why did we read this?” But we figured some of the non-US based folk might find it useful or vaguely interesting.

Especially as it can make things trickier – check out the likes of KRNO/Reno Tahoe. If you are flying All the Way to Reno then You’re Gonna be (flying) a STAR and it might involve an OPD. This airport is at a nice high elevation of 4415′, and has some decent terrain around it (the MSA is 12,000′) so there ain’t much room to mess up if you mess up your OPD.

Where else in the world can I expect these?

Eurocontrol have a whole task force dedicated to this. You can read their action plan here.

They refer to them as CCO and CDOs (constant climb or descent operations), and I’m not sure specifically which airports use them, but I’m thinking a fair old few.

5 Comments

Marc Hill says:

5 March, 2024 at 4:13 pm

I showed this to my dad who was an airline pilot. And he said they had a chart that would help with a CDA path. Basically if ATC tells you the expected miles to touch down you could apply the FPA to make the approach.

luca bandini says:

9 February, 2023 at 3:30 am

What descent angle/% are these ODP calculated for?

- Rebecca Lougheed says:
  
  9 February, 2023 at 3:52 am
  
  I do not think they are necessarily set to a specific angle as it would vary. We have not found any chart information related to them yet, but will keep seeing if anything is published
  
Richard Krulik says:

3 February, 2023 at 10:04 pm

The FAA video refers to this as OPD – Optimized Profile Decent, not ODP.
Please clarify.

Stephen Elop says:

3 February, 2023 at 8:06 am

Where precisely does one see one of the new ODPs? I looked at the approach plates for some of the airports, and could not immediately identify an example arrival.

Optimise your Descent