The spring migration takes place between mid-FEB and the end of MAY, the most active part being in APR and MAY. This migration is more dispersed and less spectacular than the autumn one. The principal direction over Belgium is NE.
The autumn migration lasts for more than three months. The first flight movements can already be seen from the end of JUL, while the last movements of any significance are completed by the end of NOV. They have a typical stream of movement with periods of relative calm interspersed with periods of very intense migration. Between mid-AUG and mid-NOV migratory birds are particularly active. The movement takes place in a mostly SW direction.
When on actual migration, most birds make long flights at often high levels in contrast to their flying at relative low altitudes during their stay in the concentration areas.
Although a great part of the bird population that is dangerous to aircraft, start migrating from concentration areas, according to radar observations migration often appears to take place over a broad front, covering nearly the entire Belgian territory.
As a result of radar observations it is known that mass migration takes place when
This can be completely in contrast to what will be observed visually.
Heavy night migration may occur early in autumn (from mid-AUG onwards) and later in spring (till the end of MAY). During the winter months sudden snow and frost may stimulate very large numbers of water- and open land birds (geese, ducks, waders, starlings, thrushes and larks) to move to the south.
The bird strike risk resulting from these winter flights (during a period of sudden thaw, in opposite direction) is particulary high in the northern part of the country.
As elsewhere in the world, headlands, inland waters and shallow estuaries attract flocks of birds for breeding, roosting and feeding at various times of the year. Within 10 NM or so of such locations concentrations of birds flying mostly below 1 000 FT may be encountered.
In order to lessen the risk of bird strikes, pilots of low flying aircraft should, whenever possible, avoid flying at less than 1 000 FT above surface level over areas where birds are likely to concentrate. Where it is necessary to fly lower than this, pilots should bear in mind that the risk of bird strike increases with speed (it is a fact that birds rarely hit an object moving slower than 80 KT).
Apart from endangering aircraft by flying close to bird colonies, the breeding of the birds may be upset and the practice should be avoided on conservation grounds. It should also be appreciated that, especially in the case of sea bird colonies, concentrations of birds may be soaring on lee waves downwind of the areas where they breed.
Identification | Area | Bird species |
---|---|---|
Ettenhovense polder | A circle, 200 M radius, centred on 511858N 0042122E | Blue throats |
Kuifeend | A circle, 1 000 M radius, centred on 511756N 0042114E | Blue throats, ducks, swans, herons, raptors |
Molsbroek | A circle, 2 000 M radius, centred on 510550N 0040130E | Waterfowls |
Zwin | A circle, 3 000 M radius, centred on 512000N 031700E | Highest concentration of birds along the coast (ducks, swans, gulls, mergansers, shorebirds) |
Military training and flight operations usually take place at low altitudes, where a lot of birds are present, especially near coasts and during migration periods. To prevent bird strikes, the Aviation Safety Directorate (ASD) of Belgian Defence has put in place a warning system in cooperation with national and/or international agencies.
The bird migration observation system is based upon the following networks and technical means:
General studies:
Radar observation:
Visual observation:
In the aerodrome vicinity zones in-flight reports by aircrews, reports by ATC, weather observers and the local Bird Control Units (BCU) remain concrete sources of information;
Warning and reporting system:
It remains a national decision to establish or not bird strike warning/risk organization and procedures for its area of responsibility. Belgian Defence has put in place a warning and reporting system in cooperation with national and/or international agencies. Its zone of responsibility has been divided in GEOREF squares and for each one a BIRDTAM can be issued;
For the squares above the Brussels FIR, the BCS within Aviation Safety Directorate is responsible to issue the BIRDTAM based upon:
For each military aerodrome and shooting range:
A Local Bird Intensity (LBI) warning can be proposed by the BCU and officially issued by the Supervisor of Flying Activities (SOF) based upon visual observations and possible local radar observations and being in force for the local very close traffic pattern of the related aerodrome. If no LBI is issued, the general BIRDTAM applicable to the GEOREF square where the aerodrome is located, remains in force.
Based on the risk level, local authorities apply flying restrictions that are published in the COMOPSAIR directive ACOT-GID-DOCSOP-ASBD-200.
The military NOF will provide bird strike risk warning (BIRDTAM) based on the following observation intensity scale:
0 | Practically no risk |
1 | Extremely small risk |
2 | Very small risk |
3 | Small risk |
4 | Fairly small risk |
5 | Fairly great risk |
6 | Great risk |
7 | Very great risk |
8 | Extremely great risk |
The intensity digit is acquired after interpretation of Meteo Radar data by ASD / BIRDTAM office (located in Beauvechain) and relayed to the military NOF (Steenokkerzeel ATCC). It relates only to the bird migration in the Brussels FIR.
The Brussels FIR is situated within the following geographic references (GEOREF):
Square defined by | ||
GEOREF | Parallels | Meridians |
NKCG | 510000N to 515959N | 0020000E to 0025959E |
NKDG | 510000N to 515959N | 0030000E to 0035959E |
NKEG | 510000N to 515959N | 0040000E to 0045959E |
NKFG | 510000N to 515959N | 0050000E to 0055959E |
NKCF | 500000N to 505959N | 0020000E to 0025959E |
NKDF | 500000N to 505959N | 0030000E to 0035959E |
NKEF | 500000N to 505959N | 0040000E to 0045959E |
NKFF | 500000N to 505959N | 0050000E to 0055959E |
NKGF | 500000N to 505959N | 0060000E to 0065959E |
NKEE | 490000N to 495959N | 0040000E to 0045959E |
NKFE | 490000N to 495959N | 0050000E to 0055959E |
NKGE | 490000N to 495959N | 0060000E to 0065959E |
BIRDTAM will only be issued when migrations reach intensity 5 or higher.
The text will include a serial number preceded by the word 'BIRDTAM'. This serial number begins, each calendar year, with 0001.
The format will be the ICAO NOTAM format with special code 'QBIRD' in the military NOTAM serie M, originator EBSZYNYX and
ITEM 'A' | FIR |
ITEM 'B' | Valid from (DTG - UTC) |
ITEM 'C’ | Valid till (DTG - UTC) |
ITEM 'E’ | BIRDTAM nr BIRD INTENSITY BELGIUM Intensity of Bird migration (see § 4.3) Geographic reference (see § 4.4) per square Additional information |
ITEM 'F’ | Lower height limit of the hazard (in feet AGL) |
ITEM 'G’ | Upper height limit of the hazard (in feet AGL) |
The BIRDTAMs are always issued with the priority ‘DD’, through the Aeronautical Fixed Telecommunication Network (AFTN) to the group address EBZZALEB.
This group address contains the following AFTN addresses:
Group Address for BIRDTAM | ||
---|---|---|
EBZZAL | IDENTIFICATION | |
1 | EBBEZPZX | W OPS BEAUVECHAIN |
2 | EBBLZPZX | W OPS KLEINE-BROGEL |
3 | EBBRYNYN | skeyes NOF |
4 | EBCIZPZX | AIS CHARLEROI/BRUSSELS SOUTH |
5 | EBCIZTZX | TWR CHARLEROI/BRUSSELS SOUTH |
6 | ETARYXYX� KRCHYXYX | BASE OPS - ATS CHIEVRES |
7 | EBFNZPZX | ATC KOKSIJDE |
8 | EBFSZPZX | W OPS FLORENNES |
9 | EBGLZGZX | AIS CRC |
10 | EBMBZPZX | W OPS MELSBROEK |
11 | EBMIZGZF | STEENOKKERZEEL ATCC ARO |
12 | EDDFYFYJ | GROUP ADDRESS |
13 | EGVCYOYX | AIDU NORTHOLT |
14 | EGZZAKXX | GROUP ADDRESS |
15 | EHZZNTXX | DUTCH GROUP ADDRESS |
16 | EKMCYOYX | KARUP |
17 | ELLXYNYX | LUXEMBOURG |
18 | ETAAYOYX | USAFE NOTAM CENTRE |
19 | ETAAZPZX | USAFE |
20 | ETCKYFYX | GROUP ADDRESS |
21 | ETCZYOYX | GERMAN MIL NOF |
22 | ETGTYTYX | MIL MET COMM CENTRE |
23 | ETNGZPZX | GEILENKIRCHEN MIL |
24 | EUECYIYN | EUROCONTROL EAD |
25 | KCNFYNYX | US NOF WASHINGTON DC |
26 | LFLFSITX | ORLEANS COMM |
27 | LFZZNQEB | GROUP ADDRESS |
28 | LIZZNCEB | GROUP ADDRESS |
29 | LPAMYNYX | LISBON MIL AIS |
30 | LSZZNAEB | SWISS GROUP |
31 | LTAAYNYX | ANKARA NOF |
32 | LZIBYWYA | GROUP ADDRESS |
33 | RKZZNKXX | KOREA GROUP |
34 | UDDDYNYX | ARMENIA NOF |
35 | UGTBYNYX | GEORGIA NOF |
36 | UTTAYNYX | UKRAINE NOF |