PPRuNe Forums

PPRuNe Forums (https://www.pprune.org/)
-   The Pacific: General Aviation & Questions (https://www.pprune.org/pacific-general-aviation-questions-91/)
-   -   TTF TEMPO (https://www.pprune.org/pacific-general-aviation-questions/543721-ttf-tempo.html)

murch21 17th Jul 2014 12:40

TTF TEMPO
 
Hello Boys and Girls,

I recently failed the IREX (by 2%... darn that tricky wording) with one of my KDR's still having me confused (even after going back over my texts and AIP)

The gist of the problem I have is, when your ETA is during a TEMPO that has the OPR to carry holding fuel (60 min) one can simply hold fuel to the end of the "30 min buffer". e.g. if arriving in the last 10 minutes of the TEMPO validity, then only 40 min holding fuel required.

My question is: if arriving in the last 10 min of a TEMPO in a TTF (no 30 min buffer) is only 10 min holding fuel or full 60 min holding fuel required?

If you have an answer that is explained by AIP / (other) references that would be great!

Ted Nugent 17th Jul 2014 13:42

10min holding fuel until the end of TEMPO validity period only.


58.2.8 The additional fuel required by paras 58.2.4 or 58.2.5 must be carried when the ETA of the aircraft at its destination or alternate falls within the period 30 minutes before the forecast commencement time to 30 minutes after the expected time of cessation of these de- teriorations. If the holding time required by paras 58.2.4 or 58.2.5 extends past 30 minutes after the forecast cessation of these deteriorations, the aircraft need only carry sufficient fuel to hold until 30 minutes after the forecast cessation time.

58.2.9 Due to the continuous weather watch provided by TTF, the 30 min- ute buffers required by paragraphs 58.2.7 and 58.2.8 do not apply. Flights which will be completed within the time of validity of the TTF may be planned wholly with reference to the destination TTF.
The above AIP references should cover it.

murch21 17th Jul 2014 22:14

That is what I thought (and answered) but failed that question... unless I missed something else in the wording of the question...

Mavtroll 17th Jul 2014 23:39

depends on whether the tempo ends at the end of the validity of the TTF or if it is mid way

Kelly Slater 18th Jul 2014 00:24

Ask, which probably means pay, for a remark or a critique of the exam.

allthecoolnamesarego 18th Jul 2014 02:48

If you are using a TTF that is valid for the last 10 mins of the flight (for the sake of argument in this case) are you legal?

According to AIP, you need to have a forecast that is valid for at least 60 after planned ETA.



1.2.5 A pilot in command must ensure that the forecasts cover the period of the flight and that the aerodrome forecasts for the destination and alternate aerodromes, to be nominated in the flight plan, are valid for a period of not less than 30 minutes before and 60 minutes after the planned ETA.

Ted Nugent 18th Jul 2014 04:27


According to AIP, you need to have a forecast that is valid for at least 60 after planned ETA.
I could be wrong but I think the following reference overrides the 60 min ref.


58.2.9 Due to the continuous weather watch provided by TTF, the 30 min- ute buffers required by paragraphs 58.2.7 and 58.2.8 do not apply. Flights which will be completed within the time of validity of the TTF may be planned wholly with reference to the destination TTF.

allthecoolnamesarego 18th Jul 2014 05:15

Agree Ted,

But... The TTF would need to be valid for 60 min after the planned ETA. So you need to get a TTF that covers that 60 min post ETA period. The 30 min buffer for any requirements is not needed if using a TTF.

Ted Nugent 18th Jul 2014 06:00


But... The TTF would need to be valid for 60 min after the planned ETA. So you need to get a TTF that covers that 60 min post ETA period. The 30 min buffer for any requirements is not needed if using a TTF.
I dont agree.


ENR 1.10 FLIGHT PLANNING 1. FLIGHT PLAN PREPARATION
The 60min after is a Pre flight requirement only, can use TTF and land within its validity period once en-route without any other requirements.

MakeItHappenCaptain 18th Jul 2014 08:46

The TAF would be valid for well after the TTF finishes. You can't "get a TTF", it is an observation that will remain in effect for up to three hours after it is made. the TAF will continue to be in effect well after the TTF expires. Any location with the facilities to enable a TTF (is is continually watched) will more than likely be a Cat A recipient (min 24 hr validity TAF) and as they are reissued every six hours....you get the drift.

Once the TTF expires, well then so does the ability to not consider the 30min buffers.

Another consideration is that if you are arriving within 30 or 60 minutes of the INTER or TEMPO (respectively) that creates an operational requirement (ie. alternate) finishing (including the buffer period), then you only need enough holding fuel to get you to the end of that buffer period. (BIG INHALE!)

For example;
If your TAF's TEMPO finishes at 0300Z and you are arriving at 0315, then you only need 15 mins holding, ie. until 0330 when the buffer finishes.:ok:

p0ngkid 2nd Feb 2016 13:51

If you have a TEMPO on a TAF valid for 0200/0400 and your ETA is 0431
That means you dont need to carry holding fuel correct?

Well, what if at 0359 the TEMPO starts, in worst case it ends at 0459. But for my ETA at 0431 I dont need to carry any holding fuel, how does this cover the TEMPO period???

If anyone can answer this, that would be much much appreciated thanks!

AerocatS2A 2nd Feb 2016 22:46

Don't over think it. The forecast for a TEMPO between 0200-0400 means they are predicting that all weather associated with the TEMPO will be finished by 0400. You then allow the 30 min buffer (for a TAF) in case they are wrong. Of course they can be more wrong than that but that is the rule.

travelator 2nd Feb 2016 23:20


Originally Posted by allthecoolnamesarego (Post 8568227)
Agree Ted,

But... The TTF would need to be valid for 60 min after the planned ETA. So you need to get a TTF that covers that 60 min post ETA period. The 30 min buffer for any requirements is not needed if using a TTF.

You have a valid forecast for eta+60 in the TAF. You are simply using the TTF for operational requirements as your eta falls inside the validity period, even if it is by only 1 minute.

Of course, common sense would need to be used when deciding if bare minimum fuel is actually appropriate.

The Green Goblin 3rd Feb 2016 01:03

You may have failed the question because the tempo/inter in the TTF posed no operational requirement.

Capt Claret 3rd Feb 2016 06:51


The forecast for a TEMPO between 0200-0400 means they are predicting that all weather associated with the TEMPO will be finished by 0400.
It ain't necessarily so.

If the TTF was issued at 0100, thus valid from 0100-0400, it is quite conceivable that the TEMPO appears to expire at 0400 simply because that's when the TTF validity expires. Only a subsequent TTF will make this apparent.

NowThatsFunny 3rd Feb 2016 09:59

For pre-flight planning, as previously mentioned, you require a valid forecast for your arrival time plus 60 minutes. This is achieved by having the TAF.

If your arrival is within the validity period of the TTF then that is what you determine your operational requirements on.

Of course if the end of the INTER/TEMPO with operational requirements coincides with the end of the validity period of the TTF then you have no indication of whether the operational requirements will cease at that time or continue into the next TTF issued while you are flying (as Capt Claret mentioned). There is the TAF but that is not as "accurate" a forecast as TTFs.

So if you have an arrival time of 0350 with a TTF valid for 0100-0400 with an operational requirement from 0300-0400 then what will you do if the TAF (valid for at least your arrival plus 60) says it's CAVOK?

I know what I'd do.

Edit: but that may not be the exam answer.

AerocatS2A 3rd Feb 2016 12:16


Originally Posted by Capt Claret (Post 9257377)
It ain't necessarily so.

If the TTF was issued at 0100, thus valid from 0100-0400, it is quite conceivable that the TEMPO appears to expire at 0400 simply because that's when the TTF validity expires. Only a subsequent TTF will make this apparent.

Yes, quite right.

glekichi 3rd Feb 2016 16:25

I've definitely experienced the opposite.

TAF said no but TTF said ok, but not valid for arrival time. Got airborne with the option of a return and made a call to divert or not when the next TTF was issued. Thankfully for the patient TTF was also good.


Originally Posted by NowThatsFunny (Post 9257501)
For pre-flight planning, as previously mentioned, you require a valid forecast for your arrival time plus 60 minutes. This is achieved by having the TAF.

If your arrival is within the validity period of the TTF then that is what you determine your operational requirements on.

Of course if the end of the INTER/TEMPO with operational requirements coincides with the end of the validity period of the TTF then you have no indication of whether the operational requirements will cease at that time or continue into the next TTF issued while you are flying (as Capt Claret mentioned). There is the TAF but that is not as "accurate" a forecast as TTFs.

So if you have an arrival time of 0350 with a TTF valid for 0100-0400 with an operational requirement from 0300-0400 then what will you do if the TAF (valid for at least your arrival plus 60) says it's CAVOK?

I know what I'd do.

Edit: but that may not be the exam answer.


swh 3rd Feb 2016 17:18


My question is: if arriving in the last 10 min of a TEMPO in a TTF (no 30 min buffer) is only 10 min holding fuel or full 60 min holding fuel required?
If you think in big aeroplane/long range operations, they may have this fuel loaded as the normal contingency. Contingency fuel once dispatched can be used at any time, but does not need to be available all the time.

Planning, and in flight are two different scenarios. No additional fuel may be required, even SYD hold fuel.

A lot of people approach these questions like they are flying a C172 on a 1hr flight, where you may need to add fuel to reach this requirement. Even a PER-SYD on a narrow body I would not be surprised if their contingency fuel exceeded that requirement.


All times are GMT. The time now is 10:25.


Copyright 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.