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Flying at BCMT (beginning of civil morning twilight)

As a side note, in Greece there used to be (up until 5 years ago) a single such time for the entire country (location: Athens), which was wrong since these times can differ in Greece approx. 20 minutes. Now every airport has its own sunrise/sunset timetable.

LGMT (Mytilene, Lesvos, Greece), Greece

I remember having made and approach and landing after sunset at Royan in France. While turning on final I still could perceive the runway quite well, and then it suddenly disappeared. It was quite impressive that it was exactly the end of the civil morning twilight when the runway vanished. The descent rate adds up with the earth turning away from the sun and hence increases the darkening rate (Climbing would increase the whitening rate on take off early in the morning).
I then enjoyed the magic of the PCL (Pilot-controlled lighting), and the entire airfield lit up just for me!

In France you may fly VFR at night provided you filed a flight plan (not always necessary, check applicable reg,). And you generally may land at unattended airfields without asking anyone.

Last Edited by Piotr_Szut at 12 Feb 19:26

When our Jodel DR1050 was legal for night flying, I logged many “Night” landings with a clear sky and an a!most full moon, which Day techniques would have allowed.
And have logged “Day” landings just before official night with rain and thick cloud where only lights were showing on the ground.
The first winter after my licence revalidation I got my Night Rating.
Essential skills for flying near official night.

Maoraigh
EGPE, United Kingdom

Guys, the OP asked a very specific question, which I’m not sure has become clear to all those providing answers yet.

The question (from my understanding) is if there is – assuming comparable weather conditions – a notable difference in lighting at the beginning of the VFR day flying period (which, in EASA-land is at the beginning of civil morning twilight, or BCMT, as the OP correctly points out) vs. the end of the VFR day flying period (which, in EASA-land is at the end of civil evening twilight, or ECET).

I can’t comment because although I often fly near ECET and I second Piotr_Szut’s observation that there is a marked difference between landing a short while before and a short while after ECET (the latter requiring night landing skills, the former not really), I usually sleep rather long and have little experience flying near BCMT.

Btw, the terms are referred to in SERA:

“Night” means the hours between the end of evening civil twilight and the beginning of morning civil twilight. 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.

Hungriger Wolf (EDHF), Germany

Patrick wrote:

“Night” means the hours between the end of evening civil twilight and the beginning of morning civil twilight.

Shouldn’t the abbreviations be EECT and BMCT? Then we would stand a chance googling them.

Last Edited by Rwy20 at 13 Feb 15:21

Rwy20 wrote:

Shouldn’t the abbreviations be EECT and BMCT? Then we would stand a chance googling them.

Answer 1: In what way does googling ECET and BCMT not work for you?

Answer 2: Interestingly, both work and yield various definitions. EECT and BMCT seem to correspond to definitions used in the US military. ECET and BCMT result in mostly German language websites. I was familiar with the latter, but not the former.

Hungriger Wolf (EDHF), Germany

Patrick wrote:

The question (from my understanding) is if there is – assuming comparable weather conditions – a notable difference in lighting at the beginning of the VFR day flying period (which, in EASA-land is at the beginning of civil morning twilight, or BCMT, as the OP correctly points out) vs. the end of the VFR day flying period (which, in EASA-land is at the end of civil evening twilight, or ECET).

Sun is 6 deg “under the horizon” BCMT and/or ECET – how should that make an astronomical difference ?
Clouds/fog (or only humidity), surface reflection (snow vs dark woods) and direction will make the difference…

...
EDM_, Germany

Isn’t there a saying ‘it gets so dark before the dawn’ ? This of course has nothing to do with astronomy, but in literature, the hour(s) before the dawn are very often referred to as the darkest hour(s) of the night.

There has to be something to it. Also in photography, the so-called ‘golden hour’ is much shorter at sunrise than at sunset. Wonder if it has to do with the cooler temps during the dawn hours.

ch.ess wrote:

Sun is 6 deg “under the horizon” BCMT and/or ECET – how should that make an astronomical difference ?

Even with the sun more than 6° under the horizon, there will be too much light to see stars clearly. That’s why astronomical twilight is defined to end when the sun is 18° below the horizon (and analogously for dawn).

Last Edited by Airborne_Again at 14 Feb 08:10
ESKC (Uppsala/Sundbro), Sweden

Done it, but very few times and only in the winter, because during summertime beginning of morning twilight would be insanely early here at Nordic latitudes. So my recollection has not a lot to do with weather or lightning at departure, but with the fact that the preflighting is done not only at the coldest time of the day, but also in almost complete darkness.

I do remember one calm morning flight with the sun rising over the Baltic Sea on a December return flight from southern Finland to Roskilde/Denmark, sipping coffee in the Dakota with my fingers slowly thawing and the OAT reading ÷28 C, listening to the commercial traffic doing CAT III approaches to Arlanda in the freezing fog below, while my flight was VMC and in unlimited visibility all the way.

Last Edited by huv at 14 Feb 08:48
huv
EKRK, Denmark
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