Why do prop planes turn away from the runway so soon

Carawaystick

Over the last few years I noticed prop planes turn away from the runway centreline very soon after takeoff. I was travelling along the r132 at the end of runway 10 in Dublin the other day and I'd say the aer arran had turned 90 degrees before it had crossed my road.

Is it to avoid turbulance or they are going slower and to get out of the way sooner or what?

TheChizler

I think it's to do with them being quieter than jets. Jets have to maintain course until they reach a certain altitude before they can change course to fly over more populated areas (or maybe changing course means they gain altitude slower and they should be doing this as fast as possible for a while), and this altitude is less for props. I could be totally wrong...

Irish Steve

Noise is a factor, but the speed aspect is also in there, it clears the departure path for faster jets more rapidly, which with traffic levels the way they are at Dublin is a significant factor these days. ATR's climb speed is in the range 170 to 190 Kts, Jets will accelerate to 250 Kts, and faster above 10,000 Ft, (bird strike issues) so an ATR ahead of a jet will mean that one or the other has to be routed away from the normal profile to allow the jet to accelerate and climb at normal speeds. The normal separation requirement is 1000 Ft vertically or 5 Miles, so by turning the props away from the centreline departure route, the separation criteria are more rapidly met.

Growler!!!

Irish Steve is correct. The prop planes (Category A/B) will climb to 750ft and make a right turn to the DUB VOR on departure from runway 28. This is to facilitate the fact that they have less climb performance and have a slower ground speed (Indicated airspeed 160kts or 170kts depending on the ATR model) than jets.

A jet (Category C/D) departure will be straight ahead until passing the OE NDB about 5 miles from the runway end before turning.

EchoIndia

Here is an SID chart for non-jet departures off runway 28. Note the "Turn at 750ft QNH" notation.
http://www.iaa.ie/safe_reg/iaip/Published%20Files/AIP%20Files/AD/Chart%20Files/EIDW/EI_AD_2_EIDW_24-9_en.pdf

VG31

I've noticed that the ATRs turn soon after takeoff (at 750ft QNH in the chart above) and fly over the city but the Dash 8s turn much later. Does anyone know why this is?

L1011

Dash 8s are significantly faster, if that changes procedures again.

Lustrum

They do this on some of the SID's in Schipol too where you're climbing straight ahead for 5NM or so, if it's busy they'll turn you off early to make way for the next departure, particularly if they're not on the same departure as you

Teebor15

The ATR 42/72 are Cat B whereas the Dash 8-400 (Flybe) are Cat C. Basically their faster.

Alaba320

Growler!!! wrote: »

Irish Steve is correct. The prop planes (Category A/B) will climb to 750ft and make a right turn to the DUB VOR on departure from runway 28. This is to facilitate the fact that they have less climb performance and have a slower ground speed (Indicated airspeed 160kts or 170kts depending on the ATR model) than jets.

A jet (Category C/D) departure will be straight ahead until passing the OE NDB about 5 miles from the runway end before turning.

You can have prop aircraft in cat C and jets in cat B. Aircraft categories have nothing to do with what means of propulsion the aircraft has, it is based on speed of the aircraft (clean stall speed X 1.3)

I'm not familiar with the Dash 8, but this could be the reason the don't make the early turns. Also just to add confusion...a turboprop which usually lies in Cat B, could end up in Cat C on a specific day, if they were heavy and icing conditions exist. This wouldn't usually affect the which SID to follow, but will certainly affect with approach plate and minimums you have in the likes of a circling approach.

Growler!!!

Alaba320 wrote: »

You can have prop aircraft in cat C and jets in cat B. Aircraft categories have nothing to do with what means of propulsion the aircraft has, it is based on speed of the aircraft (clean stall speed X 1.3)

I'm not familiar with the Dash 8, but this could be the reason the don't make the early turns. Also just to add confusion...a turboprop which usually lies in Cat B, could end up in Cat C on a specific day, if they were heavy and icing conditions exist. This wouldn't usually affect the which SID to follow, but will certainly affect with approach plate and minimums you have in the likes of a circling approach.

Thanks for that:D
The question was why do turbo props turn early. The main TP out of Dub is the ATR. Which uses the Cat A/B departures.

BonkeyDonker

Out of curiosity is there a list of aircraft that fall into each category at normal operating conditions?

eatmyshorts

There's a bit of confusion here. Aircraft Categories A/B/C/D/E are APPROACH categories. They have nothing to do with departure procedures.
They are referenced in order to comply with airspace and obstacle clearance considerations on approach procedures.

www.skybrary.aero/index.php/Approach_Speed_Categorisation

Irish Steve

eatmyshorts wrote: »

There's a bit of confusion here. Aircraft Categories A/B/C/D/E are APPROACH categories. They have nothing to do with departure procedures.
They are referenced in order to comply with airspace and obstacle clearance considerations on approach procedures.

www.skybrary.aero/index.php/Approach_Speed_Categorisation

See post 5 above, IAA DEPARTURE procedures for CAT A/B aircraft

A thru E are Aircraft PERFORMANCE categories, and the specific details refer to speeds, climb capabilities and other fundamental aspects of the way the aircraft operates, for more specific information, this is an excellent detailed reference site

https://contentzone.eurocontrol.int/aircraftperformance/

Alaba320

eatmyshorts wrote: »

There's a bit of confusion here. Aircraft Categories A/B/C/D/E are APPROACH categories. They have nothing to do with departure procedures.
They are referenced in order to comply with airspace and obstacle clearance considerations on approach procedures.

www.skybrary.aero/index.php/Approach_Speed_Categorisation

There is no confusion here, aircraft categories go for take off as well as approach.

smurfjed

There is no confusion here, aircraft categories go for take off as well as approach.[\quote]

Alaba320, that appears to be a CBT screenshot. Can anyone point me towards a regulation showing that the Approach categories are also used for takeoff.

Doors about to close, so I don't have time to google.

eatmyshorts

Alaba320 wrote: »

There is no confusion here, aircraft categories go for take off as well as approach.

SIDs at some airports like Dublin may have Category designators. However, that is nothing to do with aircraft categorisation.
Aircraft categories are only in relation to approach procedures.

gctest50

It's to take advantage of the extra lift

Since they are so ugly the ground repels them, it has been found grass and trees repel them slightly more than concrete and tarmac

eatmyshorts

gctest50 wrote: »

It's to take advantage of the extra lift

Since they are so ugly the ground repels them, it has been found grass and trees repel them slightly more than concrete and tarmac

Isn't that helicopters?

gctest50

eatmyshorts wrote: »

Isn't that helicopters?

They seem to have scarce reserves of it and run out of it far too often

Teebor15

Aircraft categories are only in relation to approach procedures.

This is incorrect. Although the approach speeds are what defines which category (A,B,C,D,E,H) an aircraft belongs in it does not mean that these categories are only used for approach procedures. They are also used for departure procedures, and holding procedures too while we're at it.

aircraft approach category
The grouping of aircraft based on speed. The categories are as follows:

(a) Category A-speed up to 90 kt;

(b) Category B-speed of 91 to 120 kt;

(c) Category C-speed of 121 to 140 kt;

(d) Category D-speed of 141 to 165 kt; and

(e) Category E-speed above 165 kts


Aircraft departure speeds are based on the above speeds and categories as well but

Remember that the manoeuvring speed specified here does not relate to Va, but instead relates in this case to the planned speed the pilot will manoeuvre the aircraft during the departure phase of flight.

http://www.skybrary.aero/index.php/Approach_Speed_Categorisation

Teebor15

Teebor15 wrote: »

This is incorrect. Although the approach speeds are what defines which category (A,B,C,D,E,H) an aircraft belongs in it does not mean that these categories are only used for approach procedures. They are also used for departure procedures, and holding procedures too while we're at it.

There's no group H by the way

Teebor15

There's no group H by the way

There is actually. Category H is for Helicopters.

Teebor15

Aircraft departure speeds are based on the above speeds and categories as well but

Quote:
Remember that the manoeuvring speed specified here does not relate to Va, but instead relates in this case to the planned speed the pilot will manoeuvre the aircraft during the departure phase of flight.
http://www.skybrary.aero/index.php/A...Categorisation

Just to add another piece of useless information, the maximum turn speeds for the different Categories of aircraft for departure procedures are based on the missed approach speed + 10% (To allow for the extra weight a departing aircraft would have versus an arriving aircraft executing a missed approach.)

Growler!!!

Deleted User wrote: »

aircraft approach category
The grouping of aircraft based on speed. The categories are as follows:

(a) Category A-speed up to 90 kt;

(b) Category B-speed of 91 to 120 kt;

(c) Category C-speed of 121 to 140 kt;

(d) Category D-speed of 141 to 165 kt; and

(e) Category E-speed above 165 kts


Aircraft departure speeds are based on the above speeds and categories as well but



http://www.skybrary.aero/index.php/Approach_Speed_Categorisation

So an ATR 72 climbing at 170kts is in Category E? Why is it turning at 750ft out of Dublin which is a category A/B departure. Unless it relates to the approach speed!

Teebor15 wrote: »

There is actually. Category H is for Helicopters.

There's a performance category A for helis. It involves a twin or larger climbing in reverse from a platform or structure, having sufficient height and speed to land back in its take off spot in the event of engine failure.

eatmyshorts

Can any one show me a reference that states that SID categories are based on Aircraft Approach Categories?
That just doesn't make sense.

eatmyshorts

Teebor15 wrote: »

This is incorrect. Although the approach speeds are what defines which category (A,B,C,D,E,H) an aircraft belongs in it does not mean that these categories are only used for approach procedures. They are also used for departure procedures, and holding procedures too while we're at it.

For holding procedures that are part of a published instrument approach procedures.
Not for enroute holding.

Teebor15

So an ATR 72 climbing at 170kts is in Category E? Why is it turning at 750ft out of Dublin which is a category A/B departure. Unless it relates to the approach speed!

No. The criteria for deciding what category an Aircraft belongs in is based on the approach speed. So an ATR 72 is Cat B. When a Cat B aircraft departs it follows the CAT B procedure. Simple. The departure speed has no bearing on what Cat Dep an aircraft follows. But adding to my useless information I posted earlier the max speed for a Cat B aircraft flying a turning departure is 165 IAS.

There's a performance category A for helis. It involves a twin or larger climbing in reverse from a platform or structure, having sufficient height and speed to land back in its take off spot in the event of engine failure.

I don't think that has anything to do with Instrument app/dep procedures which is the tread topic.

As I said earlier Category H is for Helicopters. It would be used where Instrument procedures were required for somewhere like a heliport or in rare cases a helipad at a hospital. They are not published for airports because a Helicopter come under Cat A for airports and thus will use the CAT A chart for the appropriate runway.

Hope this helps.

eatmyshorts

Teebor15 wrote: »

Just to add another piece of useless information, the maximum turn speeds for the different Categories of aircraft for departure procedures are based on the missed approach speed + 10% (To allow for the extra weight a departing aircraft would have versus an arriving aircraft executing a missed approach.)

Why would and aircraft executing a missed approach be following an SID procedure?

Teebor15

Why would and aircraft executing a missed approach be following an SID procedure?

Sorry I'm not with you...where did I say that a aircraft executing a missed approach would follow a SID?

eatmyshorts

Teebor15 wrote: »

Sorry I'm not with you...where did I say that a aircraft executing a missed approach would follow a SID?

Your post rambled a bit and that's what I got out of it.

Still, can you provide me with a reference that states that SID procedures are based on Approach Categories. There's no such statement in Jeppesen or LIDO Route manuals.

Alaba320

smurfjed wrote: »

There is no confusion here, aircraft categories go for take off as well as approach.[\quote]

Alaba320, that appears to be a CBT screenshot. Can anyone point me towards a regulation showing that the Approach categories are also used for takeoff.

Doors about to close, so I don't have time to google.

I hope when you say "doors about to close" that you mean the doors on your bus, or else you're a pax, because it's worrying to think that a qualified pilot wouldn't know that the approach categories of an aircraft determine which SID you follow. Tell me this, what does the CAT A/B refer to on a SID then? Because if there is another section of Aircraft Categories I want my money back from flight school.

Irish Steve

eatmyshorts wrote: »

Your post rambled a bit and that's what I got out of it.

Still, can you provide me with a reference that states that SID procedures are based on Approach Categories. There's no such statement in Jeppesen or LIDO Route manuals.

Post 5, there is a link to the IAA SID's for 28, for CATEGORY A/B aircraft, and there are alternative departures for Category C and D, all very clearly categorised and listed at this link, the official IAA web site

http://www.iaa.ie/safe_reg/iaip/aip_eidw_charts.htm

Alaba320

eatmyshorts wrote: »

Your post rambled a bit and that's what I got out of it.

Still, can you provide me with a reference that states that SID procedures are based on Approach Categories. There's no such statement in Jeppesen or LIDO Route manuals.

So what are they based on? Is there a different set of categories that I don't know about?

Teebor15

Your post rambled a bit and that's what I got out of it.

Rambled a bit?...Its just one sentence!!

I suggest you read it again...slowly this time!

Still, can you provide me with a reference that states that SID procedures are based on Approach Categories. There's no such statement in Jeppesen or LIDO Route manuals.

Its in one of the ICAO PANS-OPS Manuals..i'd have to go dig it out and have a look. I'm not sure there would be an online version I can point you to..there bloody expensive to get off ICAO!

Alaba320

Somebody quickly call the CAA and tell them that they have been designing SID procedures wrong all this time and to contact eatmyshorts and smurfjed (who is a pilot) if they want advice.


https://www.caa.co.uk/docs/33/CAP778.pdf

Chapter 4, Section 5.1 quote:

The recommended speed used for the nominal track in procedure design should be 210 KIAS up to 3,000 ft aal (or the end of the first turn, as appropriate), and 250 KIAS thereafter. This is found to be a suitable average to accommodate a wide mix of aircraft types. However, if an operational requirement is established to provide a separate procedure specifically for aircraft of lower performance (e.g. Category A and B aircraft) then a lower Indicated Airspeed (IAS) may be used and annotated on the procedure charts accordingly.

eatmyshorts

Much searching and referencing has led me to this.

SID aircraft categories are A/B/C/D/E/H, but these are different to Aircraft Approach Categories, even though named the same.

The max turn speed limits for SID categories are..

A 120
B 165
C 265
D 290
E 300
H 90

Which are different from approach category limits. See


So to put this to bed... the aircraft categories that SID procedures are based on are not the Aircraft Approach Categories but different, similarly named, Aircraft Departure Categories.

eatmyshorts

Alaba320 wrote: »

smurfjed wrote: »

I hope when you say "doors about to close" that you mean the doors on your bus, or else you're a pax, because it's worrying to think that a qualified pilot wouldn't know that the approach categories of an aircraft determine which SID you follow. Tell me this, what does the CAT A/B refer to on a SID then? Because if there is another section of Aircraft Categories I want my money back from flight school.

Approach Categories DO NOT determine SIDs.
Its a different category.


Now drop the attitude.

Irish Steve

eatmyshorts wrote: »

Alaba320 wrote: »

Approach Categories DO NOT determine SIDs.
Its a different category.
https://ivao.aero/training/documentation/books/SPP_APC_Departure_procedure.pdf

Now drop the attitude.

No, you drop the attitude.

IVA0 . Never heard of it, so had to look it up.

International Virtual Aviation Organisation

The International Virtual Aviation Organisation, IVAO for short, was founded in 1998 to provide an online platform for flight simulation enthusiasts to enjoy their hobby in a simulated real-world environment, in company of other people, flying or providing Air Traffic Control services.


Virtual Airlines, In other words, NOT REAL AVIATION. Your posts are more appropriate to the Virtual airlines forum

eatmyshorts

Irish Steve wrote: »

eatmyshorts wrote: »

No, you drop the attitude.

IVA0 . Never heard of it, so had to look it up.

International Virtual Aviation Organisation

The International Virtual Aviation Organisation, IVAO for short, was founded in 1998 to provide an online platform for flight simulation enthusiasts to enjoy their hobby in a simulated real-world environment, in company of other people, flying or providing Air Traffic Control services.


Virtual Airlines, In other words, NOT REAL AVIATION. Your posts are more appropriate to the Virtual airlines forum

I'll give you that, poor checking, so I've removed the references.

However, I still stand by my assertion that Departure Categories are not based on Approach Categories.

Teebor15

Much searching and referencing has led me to this.

SID aircraft categories are A/B/C/D/E/H, but these are different to Aircraft Approach Categories, even though named the same.

The max turn speed limits for SID categories are..

A 120
B 165
C 265
D 290
E 300
H 90

Which are different from approach category limits. See https://ivao.aero/training/documenta..._procedure.pdf


So to put this to bed... the aircraft categories that SID procedures are based on are not the Aircraft Approach Categories but different, similarly named, Aircraft Departure Categories.

Wrong and comical on so many levels its hard to know where to start!

Much search and referencing and the best you find is a website by kids playing pilots! Brilliant!!

So everyone..we call all rest easy now 'eatmyshorts' has put us all in our place..I mean there is no point in me digging out my ICAO references now..how could they ever compete with info from a gaming site!

I love how rather than admit he is possibly wrong..he is determined to save face by ending it here and now!

Best post I've seen in a long time...thanks!

eatmyshorts

Teebor15 wrote: »

Wrong and comical on so many levels its hard to know where to start!

Much search and referencing and the best you find is a website by kids playing pilots! Brilliant!!

So everyone..we call all rest easy now 'eatmyshorts' has put us all in our place..I mean there is no point in me digging out my ICAO references now..how could they ever compete with info from a gaming site!

I love how rather than admit he is possibly wrong..he is determined to save face by ending it here and now!

Best post I've seen in a long time...thanks!

Still waiting for your reference showing your claim is right.

Teebor15

I'll give you that, poor checking, so I've removed the references.

I'd say you would be better remove the whole post!

However, I still stand by my assertion that Departure Categories are not based on Approach Categories.

Based on what?

eatmyshorts

Teebor15 wrote: »

I'd say you would be better remove the whole post!



Based on what?

Based on 10,000 hours airline jet experience.

Funny how the 3 people posting here saying they're not related are actual professional pilots. Whereas those disagreeing aren't.

Maybe too many steroids in the gym, eh!

BonkeyDonker

Alaba320 wrote: »

Somebody quickly call the CAA and tell them that they have been designing SID procedures wrong all this time and to contact eatmyshorts and smurfjed (who is a pilot) if they want advice.


https://www.caa.co.uk/docs/33/CAP778.pdf

Chapter 4, Section 5.1 quote:

The recommended speed used for the nominal track in procedure design should be 210 KIAS up to 3,000 ft aal (or the end of the first turn, as appropriate), and 250 KIAS thereafter. This is found to be a suitable average to accommodate a wide mix of aircraft types. However, if an operational requirement is established to provide a separate procedure specifically for aircraft of lower performance (e.g. Category A and B aircraft) then a lower Indicated Airspeed (IAS) may be used and annotated on the procedure charts accordingly.

The CAA can do as they please - they operate in a different jurisdiction than the IAA. And while ICAO can set in place many of the base rules each NASP can amend them to suit their own needs - they just need to publish the differences.

Teebor15

Based on 10,000 hours airline jet experience.

Wow..now this is getting interesting. You're an airline pilot and you don't know this.

Ok..with that many hours would it be safe to assume your a Captain? So when yourself and your first officer are briefing for the Departure and there is an option of an A/B or a C/D SID which one to you brief for and why?

eatmyshorts

Teebor15 wrote: »

Wow..now this is getting interesting. You're an airline pilot and you don't know this.

Ok..with that many hours would it be safe to assume your a Captain? So when yourself and your first officer are briefing for the Departure and there is an option of an A/B or a C/D SID which one to you brief for and why?

We brief the one we're cleared to fly by ATC.
And given the fact our charts don't show a category on them, then your point is moot

Teebor15

We brief the one we're cleared to fly by ATC.
And given the fact our charts don't show a category on them, then your point is moot

Ok so its all done for you..or computer says "No" (Pilots these days).

Ok take it back a step then..say you were rostered to fly somewhere off the airline schedule..say a charter or something and you were having a look at the dep procedures and it offered you A/B or C/D. which would you choose and why?

pepe the prawn

Teebor15 wrote: »

Ok so its all done for you..or computer says "No" (Pilots these days).

easy now chief, no need to be insulting/belittling someones trade.

Teebor15

easy now chief, no need to be insulting/belittling someones trade.

It was intended to be light hearted but i can see how someone might feel otherwise. Apologies to anyone offended.