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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 operational
limitations are published in the Airplane Flight
Manuals. Since 1996, more than 395 of such
accidents were reported on the Internet alone, causing
Consequently, the vertical tail of a multi-engine airplane is usually not designed large enough for maintaining control during turns at airspeeds as low as VMCA while an engine is inoperative and the power setting on the opposite engine is maximum. During turns at asymmetrical power, performance will be lost due to the increase of sideslip or even fin stall, and control might be lost. Loss of Control In-flight cannot be prevented at low airspeeds when a high asymmetrical thrust setting is maintained. It is this knowledge that might be lost during the past 50 years.
In order to bridge the obviously existing gap in knowledge of airplane control after a propulsion system malfunction between airplane design & flight-test and airplane operations & accident investigation, a number of papers are made available for download that explain the real value of the seven types of VMC and the important conditions that are required for the Flight-Manual-published VMC(A) to be valid, in order to prevent accidents after engine failure in the future and to improve the analysis of accidents after engine failure.
A correct VMCA definition for pilots would be:
The papers presented below are written using airplane design books as used by aeronautical universities, formal FAA and EASA Flight Test Guides (ref's 2 - 4) and the asymmetrical power course used by formal Test Pilot Schools for Experimental Test Pilots and Flight Test Engineers Ref's 10 and 11 below).
What is VMCA or VMC?
Click here to open a separate window with explanation on VMCA or download and read the formal FAA and EASA Flight Test Guides and FAR and CS § 23.149 (and 25.149), the VMCA paragraphs of which are listed in and downloadable from the list of formal References below.
The following formal documents were used for writing
the papers available on this website.
1. On-line One Engine Inoperative Trainer, University
of North Dakota, click
In addition, all graduate 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 correct.
Papers with background theory
1. Controlling Airplanes after Engine Failure - Tail Design Imposed Limitations
In only 3 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. First published 2008, last updated May 2016.
Download this paper (for free)
2. Control and Performance during Asymmetrical Powered Flight
For multi-engine rated pilots.
Detailed paper in accordance with the JAA (and FAA)
Learning Objectives, FAR's and EASA CS's for
Multi-engine Rated Pilots, CPL & ATPL. Based
on Airplane Design Methods as taught by Aeronautical
Universities and on Flight Test Techniques as taught
by Experimental Test Pilot Schools.
Download this paper (for free)
3. Airplane Control and Analysis of Accidents after Engine Failure
investigators, engineering & test pilots, manual and
textbook writers, flight-instructors and pilots who want
to know it all.
Many accident investigators, engineering/ test
pilots 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
This paper, written by a Test Pilot School graduate, explains airplane control while the thrust is asymmetrical and also engine-out climb performance and the many factors that have influence on control and performance. Seven types of VMC are discussed, as are the flight-test methods to determine these minimum control speeds (VMC's). The conditional safety of VMCA and of the derived V1 and V2 are explained, because inadequate accident 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.
will 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 anymore due to the loss of
control while an engine is inoperative.
Reading and understanding this paper will prevent both the loss of control and performance after propulsion system malfunctions in the future.
Required Data for Investigating Engine Failure Related Accidents
Manual Writers and Accident Investigators may find this list (free) 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 Analyses.
To assist in reading FDR data plots more accurately, print either of these free grid sheets on a transparent sheet using a laser printer:
4. Imperfections and Deficiencies in FAA and EASA Regulations
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.
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.
This paper is also available from the
Flight Safety Foundation on the CD-ROM that contains
all EASS 2006 papers.
6. The Effect of Bank Angle and Weight on VMCA
In the papers presented above (1,
2 and 3), a few graphs showing the effect of
bank angle and weight on VMCA and on takeoff
safety speed V2 are included. These
graphs 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. This
paper presents the prediction method and includes a few
data figures. This method can be used for all
multi-engine airplanes, provided the required stability
derivative data are available.
Review of Flight and Training Manuals
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.
8. FAA-H-8083-3A/B, 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.
8a. Flying Light Twins Safely. FAA-P-8740-66.
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.
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.
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.
A limited analysis of the Engine Failure Takeoff
Procedures in the Boeing 737-200/300/400 Flight Crew
Unless specifically stated otherwise, you may download one copy of the content for informational, non-commercial and personal use only, provided you keep intact all copyright notices and do not modify the content.
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