overhauled aircraft in Odessa. More
thorough fl ight testing then continued back
home in Croatia.Testing times
Despite some media reports, the Croatian Air
Force has not changed the way it designates
its MiGs. The Defense Ministry offi cially
confi rmed to Combat Aircraft that the HRZ
MiGs are still known as the MiG-21bisD and
the MiG-21UMD.
The fi rst of the latest upgraded MiGs were
to be delivered from Odessa to Croatia in
mid-October 2013, but because of fi ghting in
Ukraine and problems with integration of the
new avionics this was severely delayed. The
fi rst two airframes actually arrived by road in
mid-April 2014. Each of the aircraft was then
tested in four fl ights:- First fl ight: testing the engine, controls and
mechanics of fl ight - Second fl ight: testing the integration of the
original and new avionics - Third fl ight: high-altitude supersonic fl ight
at over 13,000m (FL426) and speeds of
Mach 2+ - Fourth fl ight: air-to-air testing of the radar
and all systems in simulated interception
Flight testing in Croatia turned out to be a
major challenge. Col Selak reported any
anomalies, and Ukrainian technicians in
Zagreb then worked on the repairs and
fi ne-tuned the systems.
The test fl ights were then repeated and
the aircraft not handed over to the HRZ
until they met the desired
specifi cations.
Some aircraft were tested
successfully over a period
of one-and-a-half
months, but the
majority were handed over to the HRZ two or
even three months after their arrival from
Ukraine.
Two of the Croatian MiG-21bisD fi ghters
suffered major malfunctions during post-overhaul fl ight testing. HRZ serial 132
experienced serious leaks in its internal fuel
tanks while parked in a hangar. New tanks
had to be transported from Ukraine and
installed. On June 5, 2014, serial 134 suffered
a nose cone failure at supersonic speed. Col
Selak had to shut down the engine and the
aircraft began to descend rapidly. Luckily, he
managed to re-light the powerplant at lower
altitude and thus saved the jet, before
handing it over to the Ukrainian technicians
for repairs.
Furthermore, on August 5, serial 135 had a
left landing gear malfunction while
approaching Zadar-Zemunik air base on the
Dalmatian coast as it arrived to celebrate
Croatian Victory and Homeland
Thanksgiving Day. The pilot, Lt Col Stanko
Hrženjak, fi nally managed fully to extend the
gear on the second attempt and landed safely.
The aircraft was inspected and later returned
to operational service. On December 12,
2014, in the course of test-fl ying serial 118,
Col Selak felt a sudden vibration and
temporary loss of power. He elected to make
a precautionary landing back at Zagreb-Pleso,
without incident. Flying these venerable
fi ghters is clearly not without risk.
The HRZ’s sole fi ghter squadron, the
Eskadrila borbenih aviona — EBA (literally
‘combat aviation squadron’) is based on the
military side of Zagreb-Pleso International
Airport. It regularly maintains a fully armed
quick reaction alert (QRA) pair of
MiG-21bisDs under the NATO Integrated Air
and Missile Defence System (NATINAMDS).
Until a new fi ghter is decided upon, this
unique squadron will have eight MiG-21bisD
‘Fishbed-L’ single-seat fi ghters and four
MiG-21UMD ‘Mongol-B’ trainers at its
disposal.A MiG-21bisD sporting the Croatian Air
Force’s new livery for the type climbs in
full afterburner during a post-overhaul
test ight over its Zagreb-Pleso home
base. Several nav/comm/IFF antennae
distinguish the Croatian MiG-21bisD
from the original MiG-21bis ‘Fishbed-L’.
Tomislav HaraminčićThe cockpits of single-seat HRZ MiG-21s
feature a new avionics package installed in
Ukraine comprising the KFS-564A navigation
control unit (1), SN3500 primary navigation
display (2), GPS 400W (3), AN/ARC-210 digital
radio, here temporarily replaced by a TY92
High Power VHF radio (4), new analog clock
(5), and the TSC 2050 IFF system installed on
the left-hand console and not visible in the
photo. Jadranko Ećimovićhttp://www.combataircraft.net May 2015 4140-41 MiG-21 C.indd 41 19/03/2015 10:29