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Citizen observatory of aircraft overflights · Castelldefels

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The day in figures

17 overflights counted today over Castelldefels.

Overflights today
16
take-offs
0
landings
1 flight is still under review
Last wind measured
2.0 kt
From the calm, at 21:30, at the airport
Flights last night
1
From 23:00 yesterday to 07:00 today, the band the rules treat separately
The loudest aircraft today
LAmax from the official network. The meter itself says if the noise was an aircraft
Minimum altitude, median for today
895 m
At the lowest point of each pass
Overflights in 14 days
1,476
A deliberately short window: here exposure changes with the runway in use, not with the month

Right now

In the air

Watching the sky…

Today’s overflights17

19:33A20NTakeoff
19:04A339Takeoff
16:49C525Takeoff
15:53A332Takeoff
15:45A21NTakeoff

17 overflights today · and 12 more, between 10:18 and 15:08

Complaints · Castelldefels

Today’s overflights, one by one

Local time	Aircraft	Min. alt.	Thresholds crossed
19:33	A20N	2,215 m
19:04	A339	849 m
16:49	C525	966 m
15:53	A332	567 m
15:45	A21N	1,009 m
15:08	B789	810 m
13:57	A359	919 m
13:53	A333	791 m
13:37	A359	917 m
13:27	A359	948 m
13:09	A21N	889 m
11:36	EC35	549 m	Unconfirmed
12:26	A333	726 m
11:53	A359	901 m
11:38	B772	587 m
11:10	A359	910 m
10:18	B78X	849 m

The thresholds that can be crossed today are the ones written down somewhere: the 23:00–07:00 band the airport’s rules treat separately, and the 85 dB(A) that table A2 of annex III of RD 1367/2007 sets for residential land. Altitude is not one of them yet: a fixed figure would flag 93 % of the passes over one municipality and 0.4 % of those over its neighbour, which is a postcode and not a warning. A complaint is always personal: here you are handed the difficult paragraph in writing and you file it yourself, in your own name. We send nothing on anyone’s behalf.

Analytics · Castelldefels

What 60 days say

Time coming in over the neighbourhood
21.4 %
measured
15-20 %
published
297 of 1,385 hours we were able to watch, across 60 days. 55 hours with no radar are left out
And by day, from 7:00 to 23:00
31.5 %
The band when people are out in the street with the windows open: 297 of 944 hours
Daytime landings with no published cause
36.3 %
3,101 of 8,545 daytime landings over the neighbourhood. That hour’s report published no tailwind worth the name, no storm, no wind shear, no low ceiling and no poor visibility
Night departures over the neighbourhood
27
passes
0
with a wind that compels it
Across 20 separate nights, from 23:00 to 7:00. The airport’s own table does not contemplate this configuration at night
Night hours coming in over the neighbourhood
0 h
Not one hour between 23:00 and 7:00 across 60 days, out of 441 hours we were able to watch. This is a finding too
How long one of those days lasts
11.0 h
Average hours, consecutive or scattered, over the 27 days that had any. The worst reached 16 h. This is why the figure is given in hours and not in days

When we get flown over

Local hour × 60 days · Castelldefels

Tap a cell — or drag your finger across — to read that hour.

0 → 41 overflights/hDay · 07:00–23:00Night · 23:00–07:00No radar

DAYTIME LANDINGS: flights per hour against the wind

One mark per daytime hour —07:00 to 23:00— with landings over the neighbourhood · 60 days

Tap a dot —or drag your finger across the cloud— to read that hour.

Landings over the neighbourhood Tailwind on the preferred runway (kt)

No published causeThe weather report published a cause7 kt · The rules allow the change to be considered10 kt · The rules no longer require the preferred runway

116 hours of the 297 daytime hours with overflights —3,101 landings— fell to the left of 7 kt: there the airport’s weather report published no cause for leaving the preferred runway.

4 night hours are left out, with 4 landings over the neighbourhood. They are not drawn here because between 23:00 and 07:00 the preferred runway is a different one —the northern configuration— and the airport’s published rules contemplate no easterly configuration at night: there is no preferred runway being abandoned to measure the wind against, and by the daytime yardstick every one of those hours would come out with no cause by construction. They are the graver case, not the milder one, and that is why they are counted apart instead of being diluted into this cloud.

No published cause does not mean unjustified. The airport’s published rules have a fifth clause —“traffic conditions, operational needs, safety situations and the remaining weather conditions”— that carries no threshold at all, and it is enough to cover any of these hours. What the chart shows is how much of what flies over us rests on the one clause that cannot be checked. The wind is that of the LEBL METAR, taken at each hour’s reading most favourable to the airport, gusts included.

NIGHT TAKE-OFFS: measured noise of each flight against the wind

One dot per take-off over the neighbourhood —23:00 to 07:00— · 60 days

Tap a dot —or drag your finger across the cloud— to read that take-off.

Peak noise measured (dB) Tailwind on the runway preferred at night (kt)

No published causeThe weather report published a cause7 kt · The rules allow the change to be considered10 kt · The rules no longer require the preferred runwayHow loud an ordinary landing sounds

The band on the right —from 10 kt onwards, where the rules no longer require the preferred runway— is empty. Across 20 nights, the tailwind the preferred configuration would have had never once reached the threshold that releases it: the maximum was 9.0 kt.

The dashed horizontal line is the noise of an ordinary landing over this same neighbourhood, 72.9 dB. The median of these night take-offs is 79.9 dB. That is some 7 decibels above it, which at midnight and with the window open is perceived as almost twice as loud.

The median height of these take-offs is 558 m, and that of an ordinary landing over the neighbourhood, 380 m. So it is not that they pass lower: what you hear is not proximity, it is thrust —an aircraft taking off is at full power and one landing is not—.

Of these 27 night take-offs, 20 happened without the airport’s weather report publishing any of the four causes the airport’s published rules write down with a threshold. They rest on the fifth clause —“traffic conditions, operational needs, safety situations and the remaining weather conditions”— which carries no threshold and which nobody outside can check.

No published cause does not mean unjustified: the fifth clause covers any of these nights. “Published” means published in the airport’s weather report; we do not yet read maintenance notices (NOTAM), and a night closure of the preferred runway would explain whole nights without it showing here. The direction and runway axis of each flight come from radar and from our own classification, not from a declaration by the airport operator. And daytime take-offs are not included here: by day, taking off along this axis is the configuration the rules prefer, and disputing it means disputing the runway-use agreement, not the discretion of the night shift.

What this means

Aircraft crossing right now. Position is sampled every 30 seconds, so the altitude shown is the lowest seen so far and may still drop: it is provisional, not the final figure for the pass.

Every overflight of the day in a single list, most recent first. The middle column is the aircraft model and the one on the right says whether it was taking off or landing. That last one comes out hatched while it is not yet on record: the airport’s record arrives about 35 minutes late, so the most recent passes are seen before we know what they were doing. Hatched does not mean zero, it means not yet. Decibels are no longer shown here: they arrive hours after the radar and left this list hatched from top to bottom. The loudest peak of the day is in the cards below, the decibel figure for each overflight is under “Complaints”, and all of them together are in the Excel sheet you can download at the foot of the list.

Six figures drawn from the same data as the charts below, summed over the whole window instead of a single day. The first one sets what we have measured against what the administration has in writing: that aircraft come in over the neighbourhood «between 15 and 20 % of the time». It is counted in HOURS and not in days because «time» means hours: by days it would come out nearly double, and that is not what they wrote. Only hours in which the radar worked throughout are counted; blind hours are stated separately and are neither shared out nor estimated. «No published cause» means that hour’s airport report carried none of the reasons the rules set down, not that there was none: that is exactly the question one can put to the authority. Swipe sideways to see all six.

Each little square is one hour: days run horizontally, hours of the day vertically. The darker it is, the more aircraft went over during that hour. The dark vertical bands are the spells in which aircraft come in to land over the neighbourhood instead of over the inland side; that is where nearly everything is concentrated. Squares hatched with diagonals are hours without radar, and empty ones are hours that have not arrived yet: neither of them are quiet hours. Tap a square —or drag your finger— and the hour and the number of aircraft are read out below.

Each dot is one daytime hour with landings over the neighbourhood. The higher it sits, the more aircraft went over during that hour; the further right, the more tailwind there was on the runway the airport ought to be using —that is, the more reason there was not to use it—. The two vertical lines are the only thresholds the airport’s published rules put in writing: above 7 knots the change may be considered, above 10 the preferred runway is no longer required. That is why anything to the LEFT of the first line is amber: those are hours with aircraft overhead and no published cause at all. Tap a dot to read it; if several hours land on the same spot, all of them appear, most recent first. When the airport’s report also published a thunderstorm, wind shear, a low ceiling or poor visibility, the card says so; if it does not say so, it was not published. The knots carry one decimal, which is how the airport’s report stores them: that way an hour at 6.9 kt reads as what it is and not as a “7” that would look right on the threshold.

Each dot is one take-off that went over the neighbourhood between 23:00 and 07:00. The higher it sits, the louder it was: the scale is the decibels the official sound-meter network measured as that aircraft passed. The further right, the more tailwind there was on the runway the airport ought to be using at night —that is, the more reason there was not to use it—. The two vertical lines are the same written thresholds as in the chart above: 7 knots to be able to consider the change, 10 to stop requiring the preferred runway. The dashed horizontal line is not a threshold: it is how loud an ordinary landing over this neighbourhood sounds, put there so you can compare. Anything to the left of 7 knots is amber: those are take-offs with no published cause at all. Tap a dot and below you get the date, the time to the minute, the aircraft model and how high it passed; if several land on the same spot, all of them appear, most recent first. The knots carry one decimal, which is how the airport’s report stores them: that way a take-off at 6.9 kt reads as what it is and not as a “7” that would look right on the threshold.