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Flying at BCMT (beginning of civil morning twilight)

Airborne_Again wrote:

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).

“Astronomical” wasn’t referring to the different definition of twilight, rather that from the physics based on the astro-relation of earth and sun a certain angle is very likely to lead to very similar lighting conditions at both ends of the day…

...
EDM_, Germany

Patrick wrote:

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:

Haha, thank you for clarifying it again. It’s on point! ;)

huv wrote:

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.

Thx for sharing your experience :-)

It’s about 30min before sunrise and 30min after sunset.
Those are the limits (at least in Austria) you are allowed to fly day-VFR

I haven’t checked it now if there really still is a regulation Austria saying so, but it would really surprise me. In this case here, national authorities don’t have any power to overrule SERA and thus restrict day VFR flying any further than defined therein. Even bloody Germany immediately changed their national rules on that as soon as SERA came out end of 2014…

Mainz (EDFZ), Germany

EASA 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;
Freelance IRI / CB-IR Instructor
LOWG | Worldwide

As to the original question, I know it’s a while back, but this being legal, does not necessarily means that’s it’s safe. It depends a lot on the conditions!
I’ve done it a couple of time in summer when I was based in Normandy. The difficult part, for me at least, was to wake up at 3.30 in the morning. Both times, the weather was really good, with clear sky, and after doing the preflight with a handheld light, the flight itself was not problematic at all, and quite beautiful. The morning ones are easier since you will land most likely with more light, only the take-off will be with minimum light.
Now, since I’ve moved to Trondheim, doing that in summer is impossible, the sun does not go below 6° during this time :-) In winter, I did some flight ending after sunset and before the end of civil twilight. In these cases, you need to be careful, the cloud cover will have a significant impact on the amount of light you get, no clouds, you are ok until the end of the civil twilight, with clouds in the South West direction (where the sun sets in winter here), it gets darker a lot quicker!
My last flight of 2020 was in the Cub and ended at 15.15 Local time with the end of civil twilight that day being at 15.52 and it that was as far as I would feel safe and comfortable with the Cub (I know, WWII pilots would laugh at me, they flew cubs in pitch dark and landed on unprepared field, but different times:-).
Other times, I had been able to push it closer to the end of the civil twilight, with clear sky.

ENVA, Norway

As for EASA rules, Day VFR is from sunrise (-30 minutes) to sunset (+30minutes).

As for Twilight, there is:

  • Civil Twilight (6° below horizon – persons are able to see to work outside)
  • Nautical Twilight (12° below horizon – sailors can see the horizon at sea)
  • Astronomical Twilight (18° below horizon – you can see the stars in the night sky)

The gaining, and maintaining, of a FAA Night Rating are stricter than EASA.
FAR §61.57 Recent flight experience: b) Night takeoff and landing experience. . .no person may act as pilot in command of an aircraft carrying passengers during the period beginning 1 hour after sunset and ending 1 hour before sunrise, unless within the preceding 90 days that person has made at least three takeoffs and three landings to a full stop during the period beginning 1 hour after sunset and ending 1 hour before sunrise, . .

Rochester, UK, United Kingdom

HeliPilot wrote:

As for EASA rules, Day VFR is from sunrise (-30 minutes) to sunset (+30minutes).

That is a simplification rule that some countries had in national regulation pre-SERA. SERA article 2.1.97:

97. ‘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;

FCL.001 says:

‘Night’ means the period 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.

Peter_G wrote:

The gaining, and maintaining, of a FAA Night Rating are stricter than EASA.
FAR §61.57

Interestingly, there are some broad exceptions, such as for commercial (AOC) operations and for multi-pilot turbine aircraft (with some total experience conditions).

ELLX

Peter_G14-Jan-21 11:4027
The gaining, and maintaining, of a FAA Night Rating are stricter than EASA

You are incorrect as for “gaining” a night rating; FAA is greatly more simplistic and less strict. Under FAA, It’s three hours and autmatically included with your PPL (not actually a rating).

For EASA (helicopter) it’s a course of 10hrs simulated instrument, 5hrs night flying & 5hrs theory instruction (with the prerequisite of having 100 hrs (post license issue) and 60 hrs PIC.

HeliPilot wrote:

As for EASA rules, Day VFR is from sunrise (-30 minutes) to sunset (+30minutes).

Please supply the source of this. Thanks.

Freelance IRI / CB-IR Instructor
LOWG | Worldwide
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