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Day time

Dear fellow pilots!

Could someone advise, what is ICAO definition of daytime. As I remember from theory, it's from 30 minutes before sunrise till 30 minutes after sunset, isn't it? Are there any differences from JAA/EASA? And where can I find this information in national AIP.

Today I've planned my first night flight with instructor. Our departure time was 5 minutes prior to sunset from daytime airfield and it was delayed by about 20 minutes. After we've sent DLA we have received call from briefing with response from planing center, which cancelled our flight plan. That's my story...

So, I would appreciate any advises as I want to take measures against that guy, who cancelled my flight.

EVCA

I'm not sure if there is an ICAO definition....in the UK it is 30m before/after sunrise/sunset...in the US it is 1hr for, in Singapore it is 20 mins....for qualifying flights for a night rating it often relates to civil twilight....so it is up to individual member states AFAIK...so you need to check with your own CAA

YPJT, United Arab Emirates

I thought the US was the 30 min rule (as here) but the night takeoffs and landings you need to do to get your night passenger carrying currency need to be done with a 60min rule i.e. they want them to be done when it's really dark.

I think whoever cancelled the FP was wrong.

Administrator
Shoreham EGKA, United Kingdom

ICAO and JAR/EASA have a common defintion for night, so "daytime" will be the opposite:

"Night. The hours between the end of evening civil twilight and the beginning of morning civil twilight or such other period between sunset and sunrise, as may be prescribed by the appropriate authority.

Note.— Civil twilight ends in the evening when the centre of the sun’s disc is 6 degrees below the horizon and begins in the morning when the centre of the sun’s disc is 6 degrees below the horizon."

The 30-minute definition was dropped in favor of this one over ten years ago, at least in my country!

EDDS - Stuttgart

“Night” is that period between the end of evening civil twilight and the beginning of morning civil twilight. For all intents and purposes, first light should be construed as the beginning of civil twilight, and last light as the end of civil twilight. The terms “sunrise” and “sunset” have no relevance when calculating daylight operating times for the VFR pilot.

"Civil twilight" (definition) see

You should be able to find similar information in the Latvian AIP in the section that contains "daylight and darkness" graphs and tables.

The ICAO definition does not matter, it is still country specific. So assuming your flight was in Latvia, you would have to look at the country regs. SS+30 seems to be pretty much standard in Europe, though.

The ICAO definition of night is "The hours between the end of civil evening twilight and the beginning of morning civil twilight or such other period between sunset and sunrise, as may be prescribed by the appropriate authority" (my underlining).

Civil twilight is when the sun is 6 degrees below the horizon. At the equinoxes, that amounts to around 20 minutes from SS/SR, and at the winter solstice it depends hugely on your latitude - at your latitude (Riga) around 50 minutes.

Airport opening hours are an entirely different matter, though - many airports without lighting close after sunset (and it says so in the AIP), so Maybe the flight plan was cancelled because the departure airfield had officially closed?

Biggin Hill

ICAO Annex 6 Definitions page 1-7

Night:

The hours between the end of civil evening twilight and the beginning of morning civil twilight or such other period between sunset and sunrise, as may be prescribed by the appropriate authority.

[edit: correct page]

YPJT, United Arab Emirates

Airfield has now no restrictions, it was confirmed by airfield administrator just 15 minutes prior to planed departure. So, it's limited only by national regulations. I have not sr-ss table opened from Latvian AIP and they have twilight end at 1728Z. And nothing about specific day time definition.

EVCA

what_next - by my country, do you mean Germany? It's still half an hour after sunset/before sunrise there.

SERA (Single European Rules of the Air) changes this to the 6 degrees, BTW - I just checked, it is in the definitions.

Biggin Hill

what_next - by my country, do you mean Germany? It's still half an hour after sunset/before sunrise there.

Yes, Germany. It's a bit confusing, our LuftVO says +/- 30 minutes as you write, but JAR/EU/EASA - FCL/OPS by which we instruct and fly has the civil twilight (which depends on latitude and season). And now 6 degrees (which would be 18 minutes) to make it even more complicated. A good reason for getting a night or instrument rating and forget about the whole thing!

EDDS - Stuttgart
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