(Text: Michael Wegerich)
The ceiling of an aircraft (at least the static ceiling) is the greatest altitude at which the aircraft can fly level with constant flight parameters. This means that the ceiling, as the aircraft's altitude operating limit, is reached when maximum engine thrust (with afterburner) equals drag and the maximum possible lift equals the flying weight. Level flight at constant speed is therefore not possible above the static ceiling. In a zoom climb, however, an even higher – dynamic – ceiling can be reached, but with a constant loss of speed. Aerodynamically, these altitudes are a borderline region and impose the highest stress on the aircraft. The smallest mistakes can have major consequences.
For humans this altitude range is fatal within a few seconds without special equipment. Because of the low air pressure (less than a tenth of the pressure at the earth's surface), blood vessels burst and body fluids begin to boil, i.e. turn into gas. In addition, the oxygen content of the air is too low to survive.
The aircraft fuel, too, would no longer flow through the fuel lines to the engine's combustion chamber but boil, were it not kept under the necessary fuel pressure.
The pilot sits in a protective, hermetically sealed pressurised cockpit, wears a pressure suit and, if necessary, is supplied with pure oxygen under positive pressure through a special helmet (called a pressure helmet or full helmet). This full helmet also has visor heating (like the rear window heating in a car; fine, barely visible wires) and a ventilation system to prevent the visor from misting up, as it is completely sealed like a cosmonaut's helmet.
The pilot's complete equipment for such high-altitude flights is not very comfortable, but it ensures his survival in the event of depressurisation (a leak in the cockpit, e.g. due to gunfire or a technical defect) or ejection (leaving the aircraft).
The service ceiling (static ceiling) of the MiG-21SPS was 19,500 m at a speed of Mach (M) 1.8 (1.8 times the speed of sound). Our targets, also MiG-21s, flew at 18,000 m at M 1.4 (1.4 times the speed of sound).
To achieve proficiency class II (there were three, I being the highest qualification), interceptions at service ceiling had to be flown by day. Trained pilots, too, were obliged to carry out two successful interceptions at service ceiling by day or night every year. These flights were the "high school" and not every flight was successful. Sometimes it was the fighter controller's fault, sometimes the pilot's, but rarely was the equipment to blame for failure. Pilot and fighter controller – both were equally important – had to master the difficult task of building up the manoeuvre in order to engage high-altitude reconnaissance aircraft or supersonic bombers in time, before they reached their targets.
The first step in this training were the so-called M+H flights (Mach or speed and height flights). They served to familiarise pilots with the MiG's flying characteristics at altitudes up to the ceiling and at speeds up to twice the speed of sound. Along the way you also learned how to handle the high-altitude protective equipment, how to put on the pressure suit and full helmet, how to check the equipment on the ground, and the peculiarities and limitations this equipment imposed on pilots in the air. The main focus of these familiarisation flights, however, was learning the control technique when flying from subsonic into supersonic flight ("breaking the sound barrier") and applying the optimal climb profile with the lowest fuel consumption. Since you flew on afterburner for a very long time and used a great deal of fuel accelerating to supersonic speed and in the subsequent climb, every drop counted. Besides exact timing and optimal guidance by the fighter controller, the correct use of the afterburner and "clean" control technique – with the most effective flight profile – were decisive for fuel consumption. There were no large reserves, say for a "second attack". For these flights, the minimum permitted landing fuel was even reduced from 500 to 300 litres. This remaining fuel was then enough for a small circuit at most if a landing was not possible from the first approach.
As an "old" first lieutenant with proficiency class II, I had already flown M+H flights in the MiG-21F-13 and the MiG-21MF. The flying characteristics of the two MiGs were very different on these flights. The M+H flights in the MiG-21SPS were also long behind me. So I already had some experience of interceptions at service ceiling. I had completed every single ceiling interception successfully so far; even when the guidance was not optimal, I had been able to correct guidance errors with a slightly modified flight profile and suitably adapted flight parameters.
However, the interception only counted as completed if you could prove a reliable (simulated) kill on the gun camera film. That is, you had to lock onto the target in time, i.e. have it on the screen in time, and interrogate IFF to prove that it really was the enemy target. Switching to target tracking, flying into the permitted firing zone and keeping within the permissible aiming error when launching the guided missile all had to be documented. Breaking off the attack, at the latest at minimum firing range, also had to be recognisable on the film taken by a camera of the radar screen.
I had always succeeded in achieving a reliable kill, proven on the PAU gun camera film. Thanks to an optimal flight profile, supported by good guidance, I was usually able to land with a fuel reserve of over 500 l. On previous flights I pulled the MiG up at M 1.8 from 13 km, 10 km behind the target, closed to 5–6 km of my target in the climb and was already able to fire at 15–16 km altitude, switch off the afterburner and transition into a glide without climbing to the target's altitude. That saved fuel and ensured a quick, surprising attack. Critical limit parameters were not reached.
After completing the task, or when I flew as a target myself and could follow the guidance process on the radio, there was also time to enjoy the flight. It was always impressive to see the dark blue to violet sky above you. A narrow white band on the horizon separated sky and earth. The highest clouds were over 10 km below me, and between the clouds or under a cloudless sky I saw an endlessly large pale green surface. Only large lakes, cities, coastlines or the Elbe stood out from the background. Sometimes you thought you could already see the curvature of the horizon, as from space. But that was an illusion. When the sun set on the horizon, the darker edges seemed to slope downwards and the part still brightly lit by the sun rose up, as if the horizon wanted to meet the sun at that point. No matter how bad the weather was down on earth, up here a glaring sun always shone from a deep blue sky.
Once in the high supersonic range, you did not feel that you were covering more than 40 km per minute. Only the needles of the instruments revealed how fast you were really flying, and a glance at the cockpit clock made it clear how far you had already travelled. You did not even notice the uncomfortable flying equipment, the pressing and pinching pressure suit, the heated visor of the full helmet in front of your nose. Either you had to concentrate on keeping the necessary flight parameters and on the radar screen, or you were overwhelmed by the sight of the sky revealing itself in its intense colours.
It was a summer's day in 1980. Only a few cumulus clouds hid the sun over Cottbus from time to time. In view of these weather conditions, the flying supervisor decided to carry out combat training according to the first of three variants. In this variant I was scheduled for a ceiling interception. My target was flown by an "old hand", Lieutenant Colonel Rissel.
The flight had been discussed in detail in the flight preparation the day before, and actions in possible special cases, e.g. engine failure, had been prepared. The flight profile, the work with the radar and the use of the RS-2US beam-riding missile were clear.
At the "final briefing" on the flying day, the particulars for the approach and departure routes, the meteorological data for route calculation and information on air traffic control and navigation aids were given. From the flight schedule I took the exact take-off time, flight time and route number. When I went up to Lieutenant Colonel Rissel shortly after the "final briefing", he was very taciturn. He only asked whether everything was clear for me and told me when we would go to the aircraft.
45 minutes before the flight we put on our pressure suits. A sergeant of the altitude team (team for high-altitude protective and rescue equipment) helped us. Pulling on the neck ring for the full helmet almost tore all the hair from your head, because you had to squeeze through its rubber cuff, which fitted tightly around the neck. After all zips had been closed and the tensioning straps hooked in, the flying suit or ventilation suit could be pulled over the pressure suit. Put on the green skull cap, take the full helmet under your arm, and we were ready. At the evaluation centre we collected the PAU film (for recording the radar screen), and then we set off for the aircraft.
The way to the flightline (the parking area for the aircraft taking part in flight operations) was arduous. The pressure suit pulled and pressed with every movement, as it was optimised for the seated position and not for walking. Putting on the suit, walking to the aircraft and the obligatory walk-around to take over the aircraft made everyone sweat, even at normal temperatures.
In the MiG-21's cockpit, not generous in space and now even more cramped with the high-altitude equipment, the next ordeal began after the full helmet had been put on with the help of the crew chief: strapping in included putting on the harness, connecting the radio cables, the helmet heating, the pressure suit, the oxygen connections and hooking up the NAZ-7 lanyard (connecting line to the dinghy, survival pack and emergency radio). Then the function of the high-altitude protective equipment, i.e. the pressure system of suit and helmet, the helmet ventilation and 100 % oxygen with the visor closed, was checked. The pilot himself could only "put up with" this, because only then did engine start begin. By the time I had switched on the first switch, I was already soaked in sweat from this procedure.
Start-up and taxiing were routine, apart from the restricted movement and field of view in the cockpit caused by the equipment. Lieutenant Colonel Rissel – my target – had already taken off while my aircraft was still being checked for the last time by the technicians at the last-chance check point ("last chance").
My target climbed on a heading of 240 to 10,600 m. According to the procedure (specified flight sequence), he had to continue climbing south-west to 12–13 km, accelerate on afterburner to Mach 1.2 and, beyond Leipzig, turn onto a north-easterly heading while accelerating further to Mach 1.4–1.5. As my target he then had to fly – from about Torgau / Wittenberg – at 18 km at Mach 1.4 on a north-easterly heading.
I switched the cockpit environmental system (comparable to air conditioning) from automatic to cold, but only at take-off, when rpm increased, was cold air blown into the cockpit and cool air from the hoses of the ventilation suit blown onto the pressure suit. The acceleration at take-off from the afterburner and the onset of cooling were a pleasant feeling.
I followed my target on a south-westerly heading and climbed to 12,500 m. The command post gave me the order to engage afterburner and accelerate to Mach 1.2. When the afterburner had lit and speed began to increase, I took up a slight glide angle and descended at 5–10 m/s. In this way I used gravity in addition to engine thrust to get "supersonic" quickly and economically and to get quickly through the critical region of high drag coefficient around Mach 1. For a short time the Mach needle hesitated just below Mach 1, only to jump past Mach 1. Because of the shock wave error, the variometer briefly showed "climb" and the altimeter climbed by almost 1000 m. Now in the supersonic range, the aircraft accelerated ever more strongly. M 1.2 was soon reached.
If the fighter controller was experienced and had determined the point for engaging afterburner exactly, after reaching Mach 1.2 you could begin the right turn onto the north-easterly heading, accelerating in the turn so that on reaching 1.5 times the speed of sound you were on the ordered heading and exactly 18–20 km behind the target. The turn with 30–45 degrees of bank had to be flown with a lot of feel. If the bank was too shallow, the aircraft accelerated too quickly, turn radius and turn time became too large, and you came out too far behind the target and offset to the side. With too much bank, drag was too great and you did not reach the required speed. Necessary corrections of guidance or control errors led to unnecessary additional fuel consumption, which in extreme cases could mean failure to complete the task.
After rolling out of the turn I was behind the target with the expected parameters at about 13 km. The aircraft accelerated quickly. As always, I checked the engine parameters at intervals and the position of the cone, which was extending slowly and continuously. On reaching M 1.8 I had closed to 10–12 km of the target. That was the right moment to pull up towards the target, which was flying at 18 km as agreed.
I pulled the MiG's nose up and went into the climb, expecting finally to find the target on the radar screen. But the screen stayed dark. I saw no target blip! At 15 km I would otherwise already have had launch conditions for the missiles. But now I saw an empty screen. I checked the radar switches and the magnetron current again. Everything was correct. The controller reported the range shown by the ground radar station: "range to target 7 km", shortly afterwards "5 km". I became uneasy. I had never been in such a situation during a ceiling interception. I had never "botched" such an interception. I realised that I did not have much reaction time left if I was still to find the target. Suddenly I looked at the altimeter and was startled. I was at 19 km and still climbing, already 1000 m above the target. I knew I had done something wrong. But what? The antenna pattern of the MiG-21SPS radar is fixed to the aircraft axis. Because I had chosen too steep a climb angle without checking, the antenna had been pointing steeply behind – but never at – the target!
I pushed the aircraft over in the hope of still getting the target onto the screen. Then I saw the silver MiG visually, put the reticle of the optical sight on the target, switched the radar to IFF interrogation, glanced briefly at the screen and saw the target blip, recognised the lock-on conditions and pressed the lock-on button. The radar immediately switched to lock-on. The launch conditions for the RS-2US were present. All the necessary switches for simulating the missile launch were on. Meanwhile I was at the same altitude as the target and close to minimum firing range – optimal for a real launch! I pressed the trigger to fire the missile. I had to hold it for about 12.5 seconds until the beam-riding missile reached the target. Only with the trigger pressed does the gun camera run in movie mode and record the (simulated) launch completely.
Then I felt strong shaking and vibration of my aircraft. It became almost impossible to keep the target blip within the 17.5-mil circle (the circle defined the maximum permissible aiming error) for the "endlessly long" 12.5 seconds. But I managed it, and before minimum firing range I was able to turn onto the heading ordered by the command post and switch off the afterburner. In doing so, I noticed that engine rpm was only 78 % instead of 100 %. No matter where I moved the throttle, rpm stayed at 78 %.
I turned onto the ordered heading of 30 degrees, went into a glide at Mach 1.6 and reported the end of the attack to the command post in a deliberately calm voice.
I realised that the shaking had been caused by flying in the target's wake turbulence, and that this had led to a flame-out in the combustion chamber and the failure of my (only) engine. The exhaust gas temperature was at "zero". The rpm gauge showed the windmilling caused by the incoming air.
A glance at the flight data recorder switch, which said "717", made it clear to me that the engine failure could not be detected routinely. For I was flying an aircraft that had not yet been retrofitted with the "SARPP". (The "717" switch identifies the barometric recorder, which recorded only altitude and speed, not engine rpm. The SARPP, on the other hand, would have done so, as it recorded 12 parameters.) Actually I should have reported to the command post, but what for? The controller could not help me.
I thought: just stay calm, and reported the new heading to the command post. I had spent over 750 hours in the cockpit of a MiG-21, and even in this situation I felt secure and safe in the cockpit. I thought to myself: I am still so high and fast that I can try to relight the engine several times, and if it does not start, I can still report to the command post and eject.
With the engine windmilling and a constant M 1.5, I descended to 11 km and levelled the aircraft at the horizon. Without engine thrust I was soon subsonic and the altimeter wound down to 10 km. By then I had moved the throttle to "STOP", a prerequisite for relighting the engine.
Moving the throttle to "STOP" was particularly hard for me, because then the engine was definitely shut down. But to restore stable engine operation I had no choice: I had to "relight in the air", and for that the throttle had to be set to STOP. I had practised this on the flight simulator only a week earlier and felt confident.
I was at 9,600 m, checked 600 km/h indicated airspeed and switched on the "airstart" switch. To do so, however, I first had to break the thin locking wire on the switch. The green "ignition" light came on, and after 1–2 seconds I moved the throttle from "STOP" to "IDLE". I saw only the exhaust gas temperature rising, so I slowly pushed the throttle to "MAXIMUM". When I saw rpm rise to 100 % and felt the acceleration, I was relieved and switched off the "airstart" switch. That was at 9,400 m – my engine was running stably again.
I climbed to 10,650 m and flew to Cottbus for landing using the standard procedure, as if nothing special had happened.
After shutting down the engine, I complained to the crew chief about the broken locking wire on the "airstart" switch (certain switches were specially secured with thin copper wire) and said that I would not accept such an aircraft in future.
At the flight debriefing, Lieutenant Colonel Rissel only said: "Lad, you have to look outside too. We had contrails; you would have seen me much earlier." He was only right insofar as I alone had a "contrail" at 18 km. It began in the combustion chamber and was the vaporised fuel. At altitudes above 13–14 km there are usually no more contrails, and they begin 20–50 m behind the engine, not inside it.
The evaluation of the gun camera film confirmed a kill rated "very good", and the routine evaluation of the flight data recorder showed "no abnormalities". So the flight and the engine failure seemed to have been an experience (the beginnings of a (highest) category I flight incident) that only I knew about.
More than 10 years had passed and I had meanwhile been transferred to fighter wing JG-3 at Preschen. At a wing party, Major Posseldt, our weapons officer, came up to me and suddenly asked: "Tell me, you once relit an engine in the air, didn't you?" I asked back: "How do you know? I never told anyone." He answered: "I was your crew chief back then at Cottbus and after one of your flights I had to rewire the 'airstart' switch and top up the engine oxygen, which is only consumed when relighting in the air." (Major Posseldt had meanwhile studied in Moscow and was serving as senior officer for aircraft armament on the staff of JG-3.)
Then everything was clear to me. I asked: "Why didn't you rat on me back then?" He answered: "Why should I? You didn't complain about the aircraft either." That was true: the aircraft, the radar and the starting system had worked perfectly. The technical ground crew were spared many hours of pointless work because everything went as the aircraft systems intended.
Since then I have never had another engine failure, and Major Posseldt has kept our secret to this day.