Hisklig flygning i Slovenien

Ursprungligt publiceringsdatum: 2007-08-08
Ursprunglig artikelförfattare: allan.emren

Jag kommer ju att ge en fullständig skildring av årets Maltarally så småningom, men nu tänker jag beskriva en händelse så allvarlig att jag skrev en rapport.

Vare sig du som läser detta är yrkesflygare, flygelev, flygledare eller bara intresserad, vet du säkert att en flygning måste planeras noga. Speciellt gäller det om flygningen är lång och går genom områden med bergig terräng. Särskilt viktigt är att ta reda på minsta säkra höjd under olika delar av flygningen, förekomst av hinder längs färdvägen liksom att planera bränslet så att man fortfarande har tillräckliga reserver vid målet.

Under flygning från Graz till Rom med en beräknad flygtid på 2 tim 53 min passerade vi Slovenien, ett vackert land med höga berg, skummande vattenfall och mycket grönska. Men där finns också förrädiska vindar, snabbt växlande väder och dolda faror i form av kraftledningar och linbanor. Har du själv aldrig upplevt svår turbulens, så sörj inte över den saken! Det är något helt annat än att flygplanet skakar och kränger litet grann.

Här följer rapporten. Den är på engelska för att LFS enkelt skulle kunna sända delar till andra länder vid behov.



Weather conditions
Visibility >10 km
Clouds: Initially broken - overcast 5000 - 6000 ft Later CAVOK
Turbulence: Generally light or none. Locally moderate to severe.

ATS Flight plan LOWG - LIRU
Route SENDER RADLY DOL BUSER FAL TIBER
Flight plan accepted

Planned route
In addition to the reporing points of the ATS flight plan, a few additional points were defined to make sure that no intrusion into restriction areas etc would happen during the flight. The inserted point of interest here was named Ljr02E, and was inserted to make sure that the flight proceeded outside restriction area 02 in Slovenia. The intended route through Slovenia and Croatia is shown in Figure 1, in which the route is marked with purple lines.

Calculated safe altitudes for the legs were:
RADLY - DOL 4000 ft
DOL - Ljr02e 4500 ft
Ljr02e - BUSER 5500 ft

Potentially dangerous circumstances
I was directed along a route where I did not know the elevation of the terrain. As a result the ground clearance was sometimes less than desirable.

Due to turbulence, only rude following up on maps was possible. During some time periods, the aircraft was not fully controllable.

No prior knowledge about power lines, cable car lines etc was available as the actual route was not planned.

The route along which I was directed was longer than the intended. As a result, the flight time became one hour more than calculated. Thus, fuel planning became invalid.

Description of events
Contacting Ljubljana at RADLY, I was informed that clearance to proceed via DOL was denied. Instead, I was directed along a route as shown in figure 1. The route has been retrieved from the log file of the GPS, and superimposed upon the map. As is seen, this route is so far away from the planned, that all previously calculated safe altitudes and lists of obstacles became meningless.



The terrain along the given route, was higher than the altitude of the flight at several occasions. Deviations were needed to prevent collision with terrain. Figure 2 shows an approximate vertical profile along the actual flight path. In this figure, it looks like the aircraft almost touched terrain at one occasion. In reality, this did not happen. The cause for this impression is that the resolution of the elevation data base is about 0.5 nm, and the terrain very steep. The aircraft was, however, uncomfortably close to the terrain and severe turbulence was encountered in this area which made controling the flight extemely difficult.

Similarly, there was high terrain close to the aircraft in some areas where figure 2 indicates a clearance of 1000-2000 feet.



The cloud layer prevented climb to higher altitudes during the first 45 minutes.

In the areas where the path was close to high mountains, the turbulence was moderate to severe, and the aircraft was temporarily not fully controllable. Sometimes, also strong downwinds were encountered, that forced the aircraft closer to mountains than desirable.

All this was a result of the unknown height of the terrain. In mountain areas, 1000 - 2000 ft above the terrain is desirable to give enough time for counter actions in case of problems.

Due to the turbulence, the flight could not be followed properly on the map, so only visual judgement could be used to estimate height above terrain.

The lengthening of the route caused the flight time to be an hour more than calculated. Fortunately, the fuel reserves were enough to handle that.

Comments
The LJLJ terminal area is class C airspace, as is most of the airspace in Slovenia and Croatia. SE-FNC is equipped with transponder mode C and as could be judged from radio traffic, there was no excessive traffic load in the terminal area. Clearence to proceed via DOL would not have caused disturbance to other traffic, at least not if a proper altitude was chosen.

At two occasions, I requested to proceed towards BUSER. The first time was when I crossed the planned path close to VELIX. This was denied. The other was after passing LJPZ. Continuing south would have brought me to BUSER. Instead, I was directed back to the coast line.

If there are regulations, that make routes like the one I originally planned impossible, such rules do not benefit flight safety. Sooner or later they will cause fatal accidents.