Looking back at flying the Canberra – and the tale of a close shave on one of the survey flights with No.106 SPR Squadron.
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| Canberras and a HS748 belonging to No.106 SPR Squadron. (Photo : Simon Watson) |
The Canberra as a combat machine is still better than many modern day fighters. It is surprising that most pilots do not understand that it is not just speed and vintage of an aircraft that decides its combat worthiness but its maneuverability coupled with payload, range and endurance that decide whether an aircraft is suitable for war in that era. Add the weapon systems and avionics to this list.
I flew the Canberra for almost 30 years and have had the privilage of out performing the Mirage 2000 and MiG29 in close combat. Upgrade an aircraft like the Canberra with weapon systems that aircraft of today boast of and you still have a flying fortress that can stand its ground against any fighter. One has to recognise the strengths and weaknesses of one’s aircraft. Except for speed, the Canberra, even today has almost no weaknesses barring the avionics and weapons. They cannot be taken against an aircraft as they are independent of aircraft.
Single Engine Handling Characteristics
The single engine handling characteristics of the Canberra is critical below 130 knots at sea level. The asymmetric thrust is so high that it exceeds the rudder power at low speeds. In case we have an engine failure at low speeds we need to reduce power on the live engine to 50% to keep the aircraft under control. This means that the total thrust that a pilot has with him is just 25% of what he had during normal take off. While it may not be so critical for a light aircraft, it is extremely critical for a heavily loaded aircraft. The Pilot has to jettison stores/drop tanks to reduce drag and all up weight to enable the aircraft to accelerate to its minimum drag speed. This could vary from 148 knots to 190 knots, depending on the all up weight. The large variation in the minimum drag speed or other such speeds like take off and landing, is due to the fact that the maximum take off weight at 60000 lb is more than double its basic weight at 26000 lb. So single engine handling below 130 knots is tricky on the Canberra both during take off and landing.
It is the only emergency that we have on the Canberra – the rest are just major or minor unserviceabilities. Single engine emergencies have always been practiced on the Canberra. Prior to the mid 1970s, there used to a lot of fatal accidents during actual single engine approaches as well as practice approaches. We then changed the method and after that there have been virtually no accidents on the Canberra. No pilot is cleared to fly solo unless he can carry out a single engine approach and overshoot on single engine. Incidentally, approximately 80% of the 20 odd fatal/write off accidents since 1957 have been on Single-Engine actual or practice approaches. But for these accidents, the Canberra fleet in the Indian Air Force has had less than 10 accidents in which an aircraft was written off. It is a record that exceeds even the accident rate of some transport aircraft, considering that the Canberra fleet was more than 100 strong at one time. The Canberra still has the highest safety record in the Indian Air Force.
Zero Fuel Landing
Sometime during Dec 82 / January 83, I was carrying out survey flights from Bangalore. It had not been a very successful detachment as on most of the days the weather had not been conducive for survey, i.e lack of clear skies. On this particular day the weather was absolutely clear and I had planned to carry out three survey sorties that day to make up for lost time.
The first sortie was completed successfully. After landing I got the aircraft refueled partially. The full internal fuel for the Canberra PR version is 22000 lbs. According to my calculations, I needed to fly only 1 Hour and 45 minutes which would complete the full film magazine. The film magazine take 1 Hour 15 minutes to be completed. For a sortie at 30000 feet altitutde, I needed just 9500 lbs plus 4500 lb as reserve. So I got the aircraft refueled to 14000 lbs, saving around 12 minutes in the turn around of the aircraft.
The survey runs were from Tamilnadu coast till 60 NM to 80 NM south of Bangalore. During the westward runs, which started from the coast, the navigator, being inexperienced on the role, found it difficult to align with the survey runs. The first fix being available to him only on hitting the coast. So we had to make more than one attempt to align ourselves correctly as the pilot can only do a rough alignment after which the navigator has to take over though the photo sight. We not only wasted a lot of time but also consumed excess fuel.
Since our last run would be westward, I continued with our eastward run even though the fuel was below the acceptable limits. According to my calculations we would have 1500 lb left when we ended the last run south of Bangalore, at which time we would be 75 NM from Bangalore. The height distance combination was correct for a engines idling descent to Bangalore with a fuel consumption of 300 lb leaving 1200 lb for a circuit and landing.
As luck would have it the navigator again had difficulty in aligning and we repeated the alignment run successfully. I was fully aware that our fuel would now be down to approximately 1000 lb by the end of the run. It worked out as calculated. On completion of the run I put the aircraft into a descent with idling rpm at the optimum glide speed for that weight, which was 160 kts. To save fuel I switched off my starboard engine, the port engine being the critical engine. Bangalore was informed that we were rejoining after completion of the exercise and reported no traffic.
During descent, at approximately 20000 ft, the starboard low pressure (LP) warning came on. That should not have happened as I had the booster pump running. Since I was running both engines from the same fuselage tank, having emptied all other tanks, including transferring all fuel from the wing tanks to the fuselage tank, I was expecting the port LP light to also come on, indicating almost no fuel in the aircraft. I shut down the port engine also to conserve fuel. The intention was to relight the engines later on.
I skidded the aircraft sharply to allow fuel from the starboard section of the saddle tank to move to the port for the single engine approach. I told the navigator to keep us on track perfectly because of our situation and took over visually when we spotted Bangalore airfield from 40 NM. I informed Bangalore ATC of my position without announcing my predicament. At that stage I was more worried about the Court of Inquiry and its repercussions. We positioned ourselves on base leg approximately 2000 feet higher than what it should be to cater to strong winds and any errors that might crop up. I lowered my undercarriage and flaps on the base leg and once the flaps were lowered, put the aircraft into a fairly steep glide. I tried a relight on both engines with no success. The glide angle was too steep to allow fuel feed from the tank!
The speed remained between 150 and 160 kts as the aircraft altitude came down to 200 feet AGL. That’s when I raised the nose to drop the speed and let it wash off, touching down at 120 kts (30 kts higher than recommended for that weight). I did this as I needed the speed on ground to reach the dispersal. After touch down I lowered the nose and eased off to the extreme left of the runway. I braked so as to have approximately 30 to 40 kts taxying speed at the eastern link, which is the entrance to the HAL Canberra dispersal (now cargo dispersal). I turned into the taxi track with sufficient speed to roll up the taxi track and on reaching the peak breathed a sigh of relief as there was only down slope to ensure that I could roll into the parking bay at the regular speed.
There was no ground crew to receive me as I had asked them to finish their lunch and then carry out the turn around servicing. After switching off the aircraft, when I got out, my legs started shaking at the thought of what could have happened had we been just 10 NM short of the position when we lost our first engine.
It was sheer providence and thanks to the 106 Squadron’s top brass that insisted on us carrying out practice force landings on the Canberra, from as far as 100 NM from altitudes up to 48000 feet for such eventualities. It was not uncommon in the squadron to return with such low fuel figures after a survey or recce sortie.
What went wrong?
When my aircraft was refueled the actual fuel that went into it was a total of 22000 lb, a clear indication of there being just no fuel in any of the tanks. The tank in use was over reading by 1000 lb. calibrating other tanks showed that they were also in error. While it did not change the way I operated as long as I remained in the squadron, we ensured that the fuel tank gauges were calibrated regularly to ensure that no one else in the squadron ever faced this situation.
I did not fly the third sortie that day; or any other day for the rest of the detachment. Plain scared!!
Copyright © Wg Cdr Vineet Bhalla . All rights reserved. Reproduction in whole or in part in any form or medium without express written permission of Wg Cdr Vineet Bhalla is prohibited.