Issue Number 228
June 1998
A Monthly Safety Bulletin from The Office of the NASA Aviation Safety Reporting System
P.O. Box 189, Moffett Field, CA 94035-0189

"Carbon Monoxide Alert" with a Gass Mask

Most pilots are aware that carbon monoxide (CO) is a colorless, odorless and tasteless gas contained in exhaust fumes. It is also a common by-product of chemical reactions which can occur upon heating of many petroleum products and silicone-based synthetic lubricants used as aircraft oils and hydraulic fluids.

The carbon monoxide level in blood is measured through a specific blood-gas method and is reported as a percentage. The normal level of carbon monoxide produced by the body's metabolism is from 0.4-0.7%, but heavy smokers can have much higher levels. Elevated levels of carbon monoxide in the bloodstream can create the effects of hypoxia (oxygen deficiency). Here is one air carrier crew's experience with CO:

Headaches and nausea were the symptoms reported by another crew who suspected carbon monoxide exposure.

The source of the odors was not identified, but carbon monoxide probably caused the crew's symptoms. More information about hypoxia and carbon monoxide can be found in the Aeronautical Information Manual--Medical Facts for Pilots, Section 1, Para. 8-1-2 and 8-1-4.

Handy Detectors

A General Aviation pilot, thwarted by closed airport restaurants, initially thought that his nausea and dizziness during flight were due to skipping breakfast.

Aviation supply shops have no "missing breakfast detector" available at any price. However, small, lightweight carbon monoxide detectors are available for less than $10, and change colors to inform aircraft occupants of the presence of this odorless gas.

The Air Up There Is Rare

Another General Aviation pilot used oxygen delivered by nasal cannula to fend off altitude-related hypoxia.

The reporter believes that the oxygen flow rate may have been inadequate for the altitude flown. A full-size face oxygen mask might have provided more reliable delivery of correct amounts of oxygen. This reporter and other pilots of unpressurized aircraft that fly at high altitudes might consider high-altitude pressure chamber training, offered by the Air Force and the FAA. Hypoxia recognition is a beneficial by-product of this training. Information and application forms for this training may be obtained from local FAA Flight Standard District Offices. Courses are offered for small fees at appropriately equipped Air Force bases.

Wisdom From Weekend Warriors

An airline Captain traded his regular "office in the sky"­the automated cockpit of a passenger jet­for weekend flying in a high performance single-engine aircraft. Lesson learned: "Twenty years of airline operations are not necessarily good training for being a weekend warrior in a light plane!"

"Rattled" is the description another pilot used to describe to ASRS the results of a nighttime GA flight over a densely populated area. This high-time ex-military and air carrier pilot had fewer than 100 hours of GA flight experience, and had joined a local flying club only two days prior to his first cross-country flight--which he elected to make at night, although severe turbulence had been forecast and reported.

Corrective actions? Our reporter thought of many--after the fact:

Won't Kick, Does Bite

Spinning PropellerThe FAA shows hand-propping horror movies at Safety Seminars, and provides grim anecdotes of pilots who were sure they could hand-prop with impunity. One such example involved a Cessna which wiped out four (4!) tied-down aircraft before it was halted in its rampage by running into a hangar­on the opposite side of the airport!

The owner of the Aeronca Champ who reported a runaway aircraft experience to ASRS was at least somewhat aware of the airplane's propensity to take off solo, for he sought the assistance of a non-pilot. But the man was not equal to the thrust force of a Champ:

A proven safe technique for hand-propping starts is to tie down the aircraft, securely chock the main gear, and have a competent person in the cockpit standing on the brakes.


A corporate pilot reports another incident of damage by props, this one induced by misplaced chocks.Spinning Propeller

Safe operating procedure for the line person should include not leaving chocks unattended and out of their usual position near a running aircraft. However, the reporter could have assured a safer taxi by waiting for an "all clear" or other definitive signal from the line person.

ASRS Recently Issued Alerts On...
Canadair CA-RJ asymmetric wing flap failure
Malfunction of both fuel tank check valves on a BA-31
Continuing confusion over a rewritten New Jersey SID
Excessive rubber build-up on a Tennessee airport runway
ATR-42 loss of cabin pressure due to inflight electrical failure
April 1998 Report Intake
 Air Carrier Pilots 2,071
 General Aviation Pilots 719
 Controllers 82
 Cabin/Mechanics/Military/Other 97
 TOTAL 2,969