Extension of hold-over time.

[Wizofoz]

Our OM-A states that "A PCI can only be used to extend a hold-over time when the applicable minimum Hold-over time equals or exceeds 20 minutes".

This is open to some interpretation.

Take an example where the min/max hold-over times are 15/45 minutes.

If precipitation occurs after de-icing, and the 15 minute minimum hold-over time is exceeded prior to take-off,but 45 minutes isn't, the way we interpret this would mean the aircraft needs to be de-iced again.

But I wonder if the intent of the regulation is not that the hold-over time that can't be extended in this case is the MAXIMUM hold-over time, so that if you take off after 15 but before 45 minutes, you are legal provided you carry out a PCI.

How do other operators work this, and does anyone have knowledge of source documents (ICAO ANNEX??) that might be more clear?

[I-2021]

Hi Wizz,

In my outfit if you are still below the holdover time frame, a pre departure inspection is suggested. If you exceed the lower limit then the procedure becomes mandatory by either the crew or qualified personnel. From my experience it's almost impossible to do it from the flight deck during precipitations especially on a wide body. As a source of information have a look at the Transport Canada Holdover time guidelines if you haven't already. The initial part deals with all these matters and the majority of the recommendations in our ops manual come from there.

[Wizofoz]

Thanks I, yes, the Canucks are the masters at Cold Wx ops!

[yoyonow]

Wiz
I think you will find it actually says:

A PCI can only be used to extend holdover time when using
Type II, III or IV anti-icing fluids and then, only when the
applicable minimum holdover time exceeds 20 minutes.

[Wizofoz]

yoyo,

No, it's been amended to "Equals or exceeds" by FCI- 2 months ago....But my original post (now amended) was a typo- thanks for that!

Yes concerning fluid type, but that was not the problem I'm seeking information on.

[yoyonow]

Sorry wiz, misread your original sentence.

My understanding is that fluids with min holdover less than 20 mins are liable to fail too quickly to allow for the PCI and get airborne within 5 minutes. Hence the minimum requirement and the return to stand in your example.

Edited to say I don't think that I misread, I think that you edited...

[Wizofoz]

Hi Yo,

Yes I edited, but it IS "Equals or exceeds" these days.

As you state it is as the company currently interprets it.

I have a sneaking suspicion it is a misinterpretation- note the reference says "Extend A hold over time if the applicable MINIMUM hold over time".

To me, a MAXIMUM holdover time is still a holdover time.

Thus if the minimum hold over time is less than 20 minutes, you can't extend the MAXIMUM hold-over time. If it equals or exceeds 20 minutes, you CAN extend the maximum holdover time, but require an external PCI.

I may be dead wrong, but the semantics seem to imply this- thus I wondered what other operators do.

I've been through the Transport Canada docs, and can't find any reference to the 20 minutes minimum hold-over. Can anyone point to a source doc for that, or reference a paragraph in the Canadian docs?

[windowshopper2010]

Hi Wiz,

We can extend the time if the precipitation is not more than light. Moderate means no extension from the lower time.

[Buckshot16]

Wiz I hope this helps,
Chapter 11 - Holdover Time Guidelines and Associated Procedures - Transport Canada (http://www.tc.gc.ca/eng/civilaviation/publications/tp14052-chapter11-1817.htm)
Also there is another document you may want to "sift' through, try google " When in Doubt .... TP 10643 E"
http://www.tc.gc.ca/Publications/en/tp10643/pdf/hr/tp10643e.pdf
Cheers:ok:

[Wizofoz]

Thanks Buckshot- that's exactly what I needed.

Though to be honest, I still find it a little ambiguous. The way we apply it is obviously conservative, but I'm still not sure it was the original intent.

Windhopper,

Yes, I see that intent in the TC documents- maximum hold-over is for light and minimum is for moderate if the HOTs being referenced are for "Light to Moderate".

[hvogt]

does anyone have knowledge of source documents (ICAO ANNEX??)You might want to have a look at ICAO's Manual of Aircraft Ground De-icing/Anti-icing Operations (Doc 9640), which can be found on the Swiss civil aviation authority's site (http://www.bazl.admin.ch/dokumentation/grundlagen/02643/02644/index.html?lang=de).

[I-2021]

Thanks from my side to all the contributors for the highly valuable links !:ok: