ALEA Safety First Program Newsletters
The Meaning Of Slope
Limits
To understand the value of
published slope landing limitations it is
important to consider the test conditions
used to demonstrate this maximum slope
value. Testing will typically be conducted
with a wind of less than 5 knots and a
neutral lateral center of gravity. Testing
will be conducted on a firm, dry,
grass-covered slope. Neither the pilot nor
co-pilot will have abnormally large diameter
knees or legs. What a published slope
landing limitation really means is that
under the best of conditions it is possible
for a pilot using good pilotage skills to
land on the stated slope angle.
The people who wrote the FAA helicopter
certification requirements recognized that a
successful slope landing is a pilot
controlled outcome and not simply a function
of aircraft design. When conducting slope
landing operations the pilot must consider
wind direction and velocity, lateral center
of gravity, and the appearance and condition
of the landing area (loose rock, soft mud,
snow, wet grass, etc. can limit the
helicopter’s ability to “stick” on the
slope), but the limiting factor to any slope
landing is cyclic control margin. If the
pilot determines that he is approaching the
limit of lateral cyclic control margin prior
to being firmly planted on the slope with
collective reduced to low power it is his
responsibility to abort the landing attempt.
It makes no difference why the pilot is
running out of control margin, whether it’s
a wind effect or lateral center or gravity
effect, or the helicopter begins sliding
down the hill or his leg is becoming pinched
between the cyclic stick and the collective
stick or whatever; the pilot action is the
same, abort the landing attempt. For this
reason, slope landing accidents are
considered pilot error accidents.
At the time the 212 was FAA certified (more
than 35 years ago) there were not
requirements in CFR 14, FAR Part 29 to
publish slope landing limitations in the
Rotorcraft Flight Manual and to this day
there is still no FAR Part 29 requirements
to publish this information. Many later
helicopters including the Bell 412 and 430
do have published slope landing limits.
Instead of being hard limits the information
would be more accurate if the RFM stated,
“slide slope landings have been demonstrated
up to 10 degrees” or whatever the
appropriate value may be.
One reason the industry began to publish
slope landing limits for later helicopters
is because these values are typically
required information for military flight
manuals. Since many commercial pilots began
their careers as military pilots it was
thought this information would be helpful.
Since limitations must be something that a
pilot can comply with the value of
publishing a slope landing limit is
questionable. I have never heard of a pilot
flying in the mountains, then hovering and
dropping a passenger on to the proposed
landing area with some sort of slope
measurement device to determine if the slope
was within the aircraft’s published limits.
Reading the attitude indicator’s roll angle
after landing is history.
During helicopter pilot training and
certification it’s important for pilots to
learn and understand the conditions that may
limit any particular slope landing attempt.
Adverse conditions can limit the maximum
slope to a value significantly less that an
aircraft’s published slope landing limits.
SUMMARY
It is the pilot’s responsibility to maintain
control of the aircraft. If the pilot is
reaching a controllability limit as
evidenced by a pedal or other control
approaching the limit of its travel, the
pilot is at the aircraft’s limit.
The same comment may be made regarding a
helicopter’s slope landing capability.
Remember, slope landing limitations, which
may be published in the flight manual were
demonstrated under ideal conditions.
The factors that influence slope landing
capabilities are cyclic control power,
crosswind lateral center of gravity, gross
weight, and the steepness and surface
characteristics of the slope. Because the
aircraft’s controllability limitations are
evident to the pilot by the control
positions during the landing, maintaining
aircraft control defines the aircraft’s
limitations.
Reprinted from HELIPROPS HUMAN A.D. with the
permission of Bell Helicopter Textron.
Author: James M. McCollough, Technical
Resource Specialist Experimental Test Pilot.
Taxi into Position and Hold (TIPH): Guidance
for Pilots
BACKGROUND
Because of a rise in TIPH events the FAA
reexamined existing TIPH procedures. A
Safety Risk Management (SRM) panel was
convened consisting of representatives from
the Air Traffic Service and the Flight
Standards Service, and certain specialists,
including experts in aviation human factors.
The SRM panel conducted a study comprising
analysis of risk and development of
mitigations. The panel considered TIPH as it
was described in FAA Order 7110.65, Air
Traffic Control, and in FAA Order 7210.3,
Facility Operation and Administration.
The results of the panel’s study are
contained in two new FAA Notices effective
Feb. 5, 2007 (N JO 7110.456 and N JO
7210.640), and in this Guidance for Pilots.
DISCUSSION
Imminent departure. TIPH is a procedure
intended to position an airplane onto a
runway for an imminent departure. Example:
Tower: N234AR runway 24L, position and hold.
This ATC instruction is not a clearance to
takeoff.
The SRM panel’s analysis of accidents and
incidents involving airplanes holding in
position revealed that in a number of cases
two minutes or more had elapsed between the
“position and hold” instruction and an
undesirable event, usually a land-over or a
go-around. Pilots should be sensitive to the
length of time that they have been holding
in position whenever they have not been
cleared to takeoff and have not been advised
of any expected delay. After two minutes in
position it would be particularly
appropriate to query the controller about
the delay holding in position.
When instructed to “position and hold” a
pilot should expect an imminent takeoff
except when explicitly advised of a delay.
Causes for delays in position include wake
turbulence and traffic on an intersecting
runway, among others.
If a takeoff clearance is not received
within a reasonable amount of time after
“position and hold” clearance, a pilot
should contact ATC. Examples:
Airplane: Cessna 234AR holding in position
runway 24L.
or,
Airplane: Cessna 234AR holding in position
runway 24L at Bravo.
Similarly, if uncertain about any ATC
instruction or clearance a pilot should
contact ATC immediately.
Situational Awareness (SA). SA while holding
in position can be improved by closely
monitoring all radio transmissions,
especially clearances issued to other
aircraft, and the acknowledgments made by
their pilots. Pilots should be particularly
alert to another aircraft on the frequency
with a similar-sounding call sign. If it is
unclear to whom an ATC transmission is
addressed, a pilot should question ATC
immediately.
Night or reduced visibility conditions. It
is crucial at night or in other
reduced-visibility conditions that pilots be
especially vigilant when cleared to taxi
into position and hold. A pilot should scan
the full length of the runway and look for
airplanes on final approach before taxiing
onto on active runway. At any time that
there is reason for concern about a
potential conflict a pilot should contact
ATC immediately.
Multiple runways and intersecting runways.
When operations are being conducted on
multiple runways it is extremely important
to listen closely for your call sign and for
any references to your assigned runway. Be
alert to similar-sounding call signs and
acknowledge instructions to you by including
your own call sign in each acknowledgment.
When you are holding in position and are in
doubt if a takeoff clearance is intended for
you, confirm with ATC before beginning the
takeoff roll. When an airplane is holding in
position on an intersecting runway, or is
cleared to do so, ATC will issue traffic
advisories to pilots of both airplanes, (1)
your airplane and (2) the airplane holding
in position, departing, or arriving on an
intersecting runway. Examples:
Tower: Delta One, runway 4, position and
hold, traffic landing runway 31.
and,
Tower: United Five, runway 31, cleared to
land. Traffic holding in position runway 4.
Conflicts with landing traffic. If landing
traffic is a factor ATC will advise an
airplane holding in position. Such traffic
may have requested a full-stop, a
touch-and-go, a stop-and-go, or an
unrestricted low approach. Pilots should
take care to note the position of such
traffic on the final approach course or in
the local traffic area. Example:
Tower: Cessna 234AR, runway 24L, position
and hold. Traffic a Boeing 737, six miles
final.
ATC will also advise landing traffic when an
airplane is cleared to hold in position on
the same runway. Example:
Tower: Delta 1011, continue, traffic a
Cessna210 in position runway 24L.
ATC will normally withhold landing
clearances on a runway while another
airplane is holding in position on the same
runway. Never land on a runway occupied by
another aircraft of any kind, even if you
have received a landing clearance. Pilots on
final approach should not hesitate to ask
the controller about traffic on the runway
of intended landing, and should be prepared
to execute a go-around if the runway appears
to be occupied.
WORDS TO LIVE BY
Always resolve any ambiguity or confusion
concerning an ATC transmission by
questioning ATC immediately. Likewise, if
you have any doubt about your ability to
comply with an ATC instruction, advise ATC.
RECOMMENDED ACTION
Directors of safety, directors of
operations, fractional ownership program
managers, trainers and pilots should be
familiar with the improved TIPH procedures
and phraseology effective February 5, 2007.
They should work together to the extent
necessary to address TIPH, as revised, in
the manuals and training programs used by
pilots, and to apply the recommended
practices in daily operations. Key changes
include the following:
-
ATC will normally withhold landing
clearances on a runway while another
aircraft is holding on the same runway.
-
ATC will issue traffic advisories to
aircraft holding in position and to aircraft
holding, departing, or arriving on an
intersecting runway.
FOR FURTHER INFORMATION CONTACT:
Clay Hewitt
FAA
Office of Air Traffic Safety, AJS-0
800 Independence Ave. SW
Washington, DC 20591
202-267-7135
RELATED READING:
FAA Notice N JO 7110.456, Taxi into Position
and Hold (TIPH), 2/5/07
FAA Notice N JO 7210.640, Taxi into Position
and Hold (TIPH) Operations, 2/5/07
http://www.faa.gov/airports_airtraffic/air_traffic/publications/
Have a question or a comment, send it to:
safety@alea.org.
Remember – Safety First!
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