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Flashcards in H Deck (26)
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Hazardous altitudes

An inherent quality of rotating
bodies, which causes an applied force to be manifested 90°
in the direction of rotation from the point where the force
is applied.


Hazardous Inflight Weather Advisory Service (HIWAS)

Service providing recorded weather forecasts broadcast to
airborne pilots over selected VORs.


Head-up Display (HUD)

A special type of flight viewing
screen that allows the pilot to watch the flight instruments
and other data while looking through the windshield of the
aircraft for other traffic, the approach lights, or the runway



The direction in which the nose of the aircraft is pointing during flight.


Heading indicator

An instrument which senses airplane
movement and displays heading based on a 360° azimuth,
with the final zero omitted. The heading indicator, also called
a directional gyro (DG), is fundamentally a mechanical
instrument designed to facilitate the use of the magnetic
compass. The heading indicator is not affected by the forces
that make the magnetic compass difficult to interpret.



Required to accomplish a conscious, rational process when making decision. Good decision-making involves risk identification and assessment, information processing, and problem solving.


Height Above Airport (HAA)

The height of the MDA above the published airport elevation


Height Above Landing (HAL)

The height above a designated helicopter landing area used for helicopter instrument approach procedures.


Height Above Touchdown elevation (HAT)

The DA/DH or MDA above the highest runway elevation in the touchdown zone (First 3000 feet of the runway)



High frequency



Abbreviation for mercury, from the Latin hydrargyrum


High performance aircraft

An aircraft with an engine of more than 200 horsepower.


Histotoxic hypoxia

The inability of cells to effectively use oxygen. Plenty of oxygen is being transported to the cells that need it, but they are unable to use it.



A predetermined maneuver that keeps aircraft
within a specified airspace while awaiting further clearance
from ATC.


Holding pattern

A racetrack pattern, involving two turns
and two legs, used to keep an aircraft within a prescribed
airspace with respect to a geographic fix. A standard pattern
uses right turns; nonstandard patterns use left turns.



Flying the aircraft on any heading required to keep
the needle pointing to the 0° relative bearing position.


Horizontal Situation Indicator (HSI)

A flight navigation
instrument that combines the heading indicator with a CDI,
in order to provide the pilot with better situational awareness
of location with respect to the courseline.



The term, originated by inventor James Watt,
means the amount of work a horse could do in one second.
One horsepower equals 550 foot-pounds per second, or
33,000 foot-pounds per minute.


Hot start

In gas turbine engines, a start which occurs with
normal engine rotation, but exhaust temperature exceeds
prescribed limits. This is usually caused by an excessively
rich mixture in the combustor. The fuel to the engine must
be terminated immediately to prevent engine damage.


Human factors

A multidisciplinary field encompassing the
behavioral and social sciences, engineering, and physiology,
to consider the variables that influence individual and
crew performance for the purpose of optimizing human
performance and reducing errors.


Hung start

In gas turbine engines, a condition of normal
light off but with rpm remaining at some low value rather than
increasing to the normal idle rpm. This is often the result of
insufficient power to the engine from the starter. In the event
of a hung start, the engine should be shut down.



A condition that exists when landing on a
surface with standing water deeper than the tread depth of
the tires. When the brakes are applied, there is a possibility
that the brake will lock up and the tire will ride on the
surface of the water, much like a water ski. When the tires
are hydroplaning, directional control and braking action
are virtually impossible. An effective anti-skid system can
minimize the effects of hydroplaning.


Hypemic hypoxia

A type of hypoxia that is a result of
oxygen deficiency in the blood, rather than a lack of inhaled
oxygen. It can be caused by a variety of factors. Hypemic
means “not enough blood.”



Occurs when an individual is experiencing
emotional stress, fright, or pain, and the breathing rate and
depth increase, although the carbon dioxide level in the
blood is already at a reduced level. The result is an excessive
loss of carbon dioxide from the body, which can lead to
unconsciousness due to the respiratory system’s overriding
mechanism to regain control of breathing.



A state of oxygen deficiency in the body sufficient
to impair functions of the brain and other organs.


Hypoxic hypoxia

This type of hypoxia is a result of
insufficient oxygen available to the lungs. A decrease of
oxygen molecules at sufficient pressure can lead to hypoxic