Publications by AvioConsult for download
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All across the globe, accidents with both small and
big multi-engine airplanes continue to happen quite
frequently following the failure of an engine during
takeoff, go-around, approach for landing and during
engine-out training, despite the fact that all airplane
types are thoroughly flight-tested, and emergency procedures and airspeed
limitations are published in the Airplane Flight
Manuals. Since 1996, more than 500 of such
accidents were reported on the Internet alone, causing
more than 4,000 casualties.
The cause of these
accidents is that the minimum
control speed in the air
(VMC or better VMCA)
of multi-engine airplanes is considered to be a safe minimum speed for maintaining
control when an engine fails or is inoperative, including during turns, but
VMC(A) is a safe minimum speed for
maintaining straight flight only, while banking a few degrees into the good engine when the asymmetrical thrust is maximal.
The accidents could have been prevented if pilots and investigators would have had a bit more understanding on the subject of flight with an inoperative engine, but the pilots are not to blame, knowledge just faded away during the past 50 years in flight and investigator training.
To again increase the level of knowledge of pilots and investigators to a level required to be able to prevent accidents after engine failure, the papers presented below thoroughly explain VMCA, including the conditions under which it is valid and the factors that affect the magnitude of VMCA and therewith performance in-flight. Investigators will also find several analyses of engine failure related accidents.
The papers are written
using airplane design books by Dr. Jan Roskam (KU), as used by aeronautical universities, the formal FAA and EASA Flight Test Guides (Ref's 2 - 4 below) and
the Engine Out or Asymmetrical Power Courses used by formal Test Pilot
Schools for teaching and training Experimental Test Pilots and Flight Test
Engineers, for which download links are provided below (Ref's 10 and 11), or on the Links page (for the full Flying Qualities courses).
In addition, several reviews of other flight and training manuals are provided below, not to apportion blame or liability, but to learn from.
VMCA is explained in an increasing level of detail in the papers #1 to #3 presented below and also briefly on the VMCA page.
On YouTube, a video lecture can be viewed that explains VMCA and reviews two accidents.
A pdf file with slides and script used in this video can be downloaded
Papers with background theory
In only 4 pages, the most important operating
limitations for flight with an inoperative engine, that
are consequences of the methods used to design the
vertical tail of a multi-engine airplane, and the
experimental flight test to determine the minimum control speed in the air (VMCA), are briefly explained to get a better appreciation of VMCA. First published 2008, last updated Jan. 2023.
Download this paper
For multi-engine rated pilots to learn about the real value of VMCA and engine-out flight, including improved definitions and emergency procedures.
Detailed paper in accordance with the JAA (and FAA)
Learning Objectives CPL & ATPL, based on FAR's and EASA CS's
and Airplane Design Methods as taught by Aeronautical
Universities and on Flight Test Techniques as taught
by Experimental Test Pilot Schools.
29 pages, 28 figures, 1.7 MB pdf. First
published January 2012, updated Jan. 2023.
Download this paper
For accident investigators, engineering & test pilots, flight instructors and manual and
textbook writers, flight-instructors and pilots who want
to know it all. This paper is a bit more scientific.
Published May 2012, updated Jan. 2023. 85 pages.
Many accident and air safety investigators, engineering test
pilots, flight instructors and Flight Manual writers explain and use the VMCA
of an airplane not in the same way as airplane design
engineers, experimental test pilots and flight test
engineers do. This knowledge gap is the real cause of many, if not all, accidents after engine failure, reason why this gap needs to be bridged to prevent many accidents and fatalities after engine failure in the future, which is the objective of this document.
To the opinion of AvioConsult, the
limitations and conditions used during designing and
flight-testing a multi-engine airplane are not
appropriately passed on anymore to (airline) pilots in manuals
and during flight training. Many pilots,
investigators and manual writers just use text out of
Airworthiness Standards and Regulations (Part 23, 25) that are intended for
designing and for the certification of airplanes, but
that are definitely inappropriate for operational use.
This document not only explains airplane control - while the thrust is
asymmetrical - but also engine-out climb performance and
the many factors that have influence on control and
Five types of minimum control speed (VMC)
are discussed, as are the flight-test methods to
The conditional safety of VMCA and of the
derived VR and V2 are explained,
because inadequate accident or safety reports show this is
required. A few incorrect definitions of VMCA
in Flight and Operating Manuals are discussed as are
inappropriate engine emergency procedures. Training and
demonstration of VMCA
in-flight, including cautions, are included as well.
Included in this document are detailed analyses of 6 engine failure accidents that actually
happened. Three of these fatal accidents (EMB-120ER, Saab SF-340B, Jetstream 4100) are
analysed step by step using Flight Data Recorder (FDR) data as illustrated in the
will, after reading this document, understand the conditions for which VMCA,
VR and V2 are valid much
better, will improve airplane control after engine
failure, know how to achieve best climb performance
and will never crash due to the loss of
control while an engine is inoperative.
Airplane accident and air safety investigators will be able to
improve the analysis of airplane accidents caused by a propulsion system malfunction
and write much better and appropriate conclusions and recommendations in accident
investigation reports. These reports will become much more valuable for preventing
propulsion system malfunction related accidents and incidents in the future.
Accident Investigators and Manual Writers may find
this list of use for verifying
whether Flight and Ops Manual data on
engine-out flight are complete, and for
making sure all data is available for Engine
Failure Related Accident Investigations and
Manual and procedure writers will
understand VMC's much better and use the
gained knowledge to improve definitions of VMC's
and engine failure procedures in Flight and
will understand engine-out performance and the
real value of the VMC's, that are published in the limitations section
in all Flight Manuals of multi-engine airplanes, as
well as the conditions for which VMC's
Reading and understanding
this paper will prevent both the loss of control and
performance after propulsion system malfunctions in
Download this valuable document | Top
A paper that resulted from the research for the
papers presented above. It presents and explains
imperfections found in aviation regulations that
might lead to accidents after engine failure and
includes ready-to-copy suggestions for improvement.
Download this paper | Top
A paper presented to the European Aviation Safety
Seminar of the Flight Safety Foundation in Athens,
Greece in March 2006. The paper addresses the 4
errors that can be found in the definition of VMCA
in the Flight Manual of almost all airplanes and
explains that there is an important condition for
both the minimum control speed VMCA and
the takeoff safety speed V2 to be valid.
Download this paper | Top
This paper is also available from the
Flight Safety Foundation on the CD-ROM that contains
all EASS 2006 papers.
In the papers presented above (1,
2 and 3), a few charts showing the effect of
bank angle and weight on VMCA and on takeoff
safety speed V2 are included. These
charts were calculated using a prediction method that is
also used by experimental test pilots and flight test
engineers before conducting the flight-tests to
in order to learn about limitations, etc. that
might be encountered during the test flights.
paper presents the prediction method and includes a few
data figures that are also useful for pilots of two- and four-engine airplanes, because it tells what AFMs no longer do. This method can be used for all multi-engine airplanes, provided the required stability
derivative data are available. If you download this paper, please also download paper #3.
Download this paper | Top
The FAA Course Notes Multi-Engine Safety Review that
is presented on the FAASafety website, was reviewed by
AvioConsult using the knowledge of experimental flight
testing. The Course notes -
as of Aug. 2012 - do not agree with Flight Test
Techniques used to determine VMCA
as taught at Test Pilot Schools (ref's 10 and 11
above) and as published in FAA Flight Test Guides in
Advisory Circulars (references 2 and 4 above).
This paper presents many suggestions for improvement
which are definitely required to improve the Notes and
therewith flight safety.
Download this paper with recommendations for improvement | Top
Chapter 12, Transition to Multi-engine Airplanes
Airplane Flying Handbook FAA-H-8083-3A/B, Chapter 12
"is devoted to the factors associated with the
operation of small multi-engine airplanes".
This Chapter was also reviewed by AvioConsult
using the knowledge of experimental flight
testing. This Chapter - as
of Aug. 2012 - regrettably does neither agree with the
design methods for sizing the vertical tail of
multi-engine airplanes, as taught at aeronautical
universities, nor with the Flight Test Techniques used
to determine the engine-inoperative flying qualities,
including VMCA, as taught at Test Pilot
Schools (ref's 10 and 11 above) and not even as
published in FAA Flight Test Guides in Advisory
Circulars (ref's 2 and 4 above). Besides a
review, this paper presents many suggestions for
improvement which are definitely required to improve the
transition to multi-engine airplanes and prevent
accidents after engine failure.
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This publication provides the aviation community with
safety information, but must be improved to really
increase safety and reduce the rate of engine failure
related accidents. The recommended improvements are
included in text boxes.
Download this paper with recommendations for improvement
9. CASA CAAP 5.23-2(0),
Multi-engine Aeroplane Operations and Training.
This document was referenced in the accident report of
a PA-31P-350 in Bankstown, 15 June 2010 and reviewed.
Although all ingredients of flight with an inoperative
engine are included, somehow it became clear that VMCA/
& VMC and the conditions that apply with
these minimum control speeds were not clear to the
authors of the accident report, and hence will not be
understood by pilots, resulting again in accidents.
Improvement is definitely required, therefore this paper
also presents suggestions for improvement.
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A limited review of PA-44-180 Seminole documents, as
used by flight schools (and by other PA-44 owners).
It should also be useful to operators of other
multi-engine airplane types.
Download this paper | Top
A limited analysis of the Engine Failure Takeoff
Procedures in the Boeing 737-200/300/400 Flight Crew
This analysis was written following a review of the
accident investigation report of the accident with
an Algerian 737 on 6 March 2003.
Download this analysis |
AvioConsult was invited to present this paper during the Safety and Procedures Forum of Eurocontrol in Brussels,
4 - 5 June 2019, about inappropriate control speed definitions and engine emergency procedures in airplane
flight manuals and multi-engine course books, and why multi-disciplinary knowledge is required to improve.
Download this paper |
The 30 min. presentation was recorded on video, view here. A pdf with the PowerPoint slides can also be downloaded from SKYbrary here.
The PowerPoint presentation is also available for download here.
A few more slides were added. You should enable the macros for the animations to work properly.
To reduce the size of the file, the two videos are not embedded, but accessible
via external links.
Several ATR pilots asked AvioConsult to review their manuals on the subject of engine-out operations, after having read the papers on this website. They suspected the takeoff and go-around speeds to be too low. Not only the AFM was critically reviewed, but also the ATR Performance Guide. The conclusion is that V2, VFTO and Go-around speeds are indeed too low and are not calculated as required by EASA and FAA Regulations. The cause might be that the real meaning of VMCA, and the flight restrictions that come with it, are not known to the performance engineers and manual writers. To the opinion of AvioConsult, the manuals were not written with care. These conclusions also apply to the ATR FCOM and QRH. Convince yourself, and...
Download this review |
Following an accident with a DA 42 airplane in Slovakia on 22 Feb. 2023 during engine-out training (as was spoken of in the local media), AvioConsult became curious whether its Airplane Flight Manual would be correct on the subject of engine-out operations and be in agreement with EASA Flight Test Guides. A limited review was conducted after which the conclusion is: regrettably it's not. This review is loaded with explanations to learn from and to help improve the manual; it is not written to apportion blame or liability. Many remarks apply to flight manuals of other multi-engine airplane types as well.
Download this review | Top
The following formal documents were used for writing
the papers available on this website.
A few comment boxes are inserted on the pages of references 2 - 6
1. On-line One Engine Inoperative Aerodynamics, University of North Dakota,
2. FAA Flight Test
Guide, AC23-8C, pages on VMCA testing,
3. EASA Certification Specification 23,
Flight Test Guide , VMCA testing,
4. FAA Flight Test
Guide, AC25-7C, pages on VMCA testing,
5. FAA Federal Aviation Regulations Part
23.149 on VMCA,
6. EASA Certification Specification § 23.149
7. FAA Federal Aviation Regulations Part 23,
8. EASA Certification Specification 23,
9. Airplane Design, Dr. Jan Roskam,
University of Kansas/DARcorporation,
10. US Naval Test Pilot School,
Flight Test Manual 106 Chapter 6 Asym Power, pdf,
11. USAF Test Pilot School, ADA170959
Ch. 11 Engine-Out Theory, pdf,
The US Naval and Air Force Test Pilot Schools have approved their course books for public release; links for download of the full course books are provided on the Links page. Links to the complete Flight Test Guides are provided there as well.
In addition, all graduate Experimental Test Pilots and Flight Test Engineers of the major Test
Pilot Schools in the USA, UK and FR will be able to confirm that the papers presented on this website are indeed in accordance with flight test techniques and guides.
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