The Deaf vs. The Colorblind

If one thinks about such things, there is no reason that either
hearing or the ability to perceive red from green are really required
intrinsically to fly an airplane.

But in one way the two groups have a conflict. Tower signal lights are
used for signalling aircraft that are NORDO, having red and green
lights. These are the very colors not separable by victims of the most
common type of colorblindness. Retiring the signal lights would be
beneficial to the colorblind, but devastating to the deaf.

In the modern digital world, neither audio nor colored lights provide
optimum interface with ATC. Each aircraft could be equipped with a data
link, and in nonaviation quantities very cheaply. However, everything
in a light aircraft costs stupid money because of the usual reasons and
really because pilots will pay it or not fly.

On Wed, 16 Aug 2006 09:50:26 -0700, Bret Ludwig wrote:

[snip]
But in one way the two groups have a conflict. Tower signal lights are
used for signalling aircraft that are NORDO, having red and green
lights. These are the very colors not separable by victims of the most
common type of colorblindness. Retiring the signal lights would be
beneficial to the colorblind, but devastating to the deaf.

If they would just change the color of one of the lights, most everyone
would be happy. If they changed the white or green light to be blue or
yellow, I think it would be fine. I'm just not sure if those colors can
be seen as far away as white/green light (doubtful). Of course, that also
implies changing the color of one position light on planes and owners may
squawk at that.

Signal lights, in of themselves, are not problematic. It's the dang
colors they picked which is the problem.


Greg

Bret Ludwig wrote:

But in one way the two groups have a conflict. Tower signal lights are
used for signalling aircraft that are NORDO, having red and green
lights. These are the very colors not separable by victims of the most
common type of colorblindness.

actually, no, you are wrong; the two colors most commonly
confused by the most common type of colorblindness (I presume
you are refering to protanomalous vision) are in practice
the white and green lights; and if you remember what these
mean in flight -- which most pilots don't :-) -- you'll see
that it would not be a problem;

besides, why would you want to 'retire' one system or the
other? the light gun is probably the least expensive piece
of equipment in the tower, lasts for ever, and is easily
operated -- they even have a placard to remind the controler
using it the meaning of the signals -- because many controlers
don't remember either :-)

--Sylvain

On 16 Aug 2006 09:50:26 -0700, "Bret Ludwig"
wrote in .com:

Each aircraft could be equipped with a data
link, and in nonaviation quantities very cheaply.

Please explain how a data link would be useful in controlling an
aircraft that has lost communication capability due to electrical
system failure.

Larry Dighera wrote:

Please explain how a data link would be useful in controlling an
aircraft that has lost communication capability due to electrical
system failure.

the same way one would for *any* aircraft that has lost communication
capability as described in AIM 6-4-1 for instance?

--Sylvain

These are the very colors not separable by victims of the most
common type of colorblindness.

That's probably why they were selected.

My understanding of color vision is that (aside from the rods) there are
three different kinds of cones in the eye - each optimized for a
different wavelength. This is what results in "primary colors". So, in
a sense, the primary colors are "as far apart as you can get", and
people with normal vision should be able to tell them apart the easiest.
Thus they make a good choice for discernment, where "closer" colors
are less good.

Colorblindness (or more accurately "anomolous color sensitivity") has to
do with problems with these cone types, or sometimes the lack of certain
cone types. (There are individuals who have four cone types, they see
different primary colors, perhaps even outside our range of vision.)
So, if the problem is with the very cones we've chosen to make the
colors "as far apart as possible", then those two colors are
indistinguishable. There is, in effect, a lack of redundancy in this
color choice. I don't know whether or not this was considered when the
choice was made.

I've noticed myself that the green (in airport beacons) is often not a
well saturated green, and the green (on wingtips) is often blue.
Perhaps secondary colors would work better for colorblind people while
not being hard to distinguish for normally sighted people.

Jose
--
The monkey turns the crank and thinks he's making the music.
for Email, make the obvious change in the address.

On Wed, 16 Aug 2006 19:19:22 -0700, Sylvain wrote in
:

Larry Dighera wrote:

Please explain how a data link would be useful in controlling an
aircraft that has lost communication capability due to electrical
system failure.

the same way one would for *any* aircraft that has lost communication
capability as described in AIM 6-4-1 for instance?


Please explain how aircraft that has lost (data link and all radio)
communication capability due to electrical system failure will be able
to receive the green 'cleared to land' light gun signal upon arrival
if light guns are eliminated as suggested.

Larry Dighera wrote:

Please explain how aircraft that has lost (data link and all radio)
communication capability due to electrical system failure will be able
to receive the green 'cleared to land' light gun signal upon arrival
if light guns are eliminated as suggested.

one, nobody suggests eliminating the light guns, and two, the answer
to your question is spelled out better than I could in AIM 6-4-1 as
already mentioned, just read it.

--Sylvain

On Thu, 17 Aug 2006 08:41:52 -0700, Sylvain wrote in
:

Larry Dighera wrote:

Please explain how aircraft that has lost (data link and all radio)
communication capability due to electrical system failure will be able
to receive the green 'cleared to land' light gun signal upon arrival
if light guns are eliminated as suggested.

one, nobody suggests eliminating the light guns,

On 16 Aug 2006 09:50:26 -0700, "Bret Ludwig"
wrote in .com:

Retiring the signal lights would be beneficial to the colorblind,
but devastating to the deaf.

and two, the answer to your question is spelled out better than I could
in AIM 6-4-1 as already mentioned, just read it.


Perhaps you'd be good enough to point out the part of AIM 6-4-1 that
exempts a flight from receiving a clearance to land from ATC at
towered airports:


http://www.faa.gov/ATpubs/AIM/Chap6/aim0604.html#6-4-1
Section 4. Two-way Radio Communications Failure
6-4-1. Two-way Radio Communications Failure

a. It is virtually impossible to provide regulations and procedures
applicable to all possible situations associated with two-way radio
communications failure. During two-way radio communications failure,
when confronted by a situation not covered in the regulation, pilots
are expected to exercise good judgment in whatever action they elect
to take. Should the situation so dictate they should not be reluctant
to use the emergency action contained in 14 CFR Section 91.3(b).

b. Whether two-way communications failure constitutes an emergency
depends on the circumstances, and in any event, it is a determination
made by the pilot. 14 CFR Section 91.3(b) authorizes a pilot to
deviate from any rule in Subparts A and B to the extent required to
meet an emergency.

c. In the event of two-way radio communications failure, ATC service
will be provided on the basis that the pilot is operating in
accordance with 14 CFR Section 91.185. A pilot experiencing two-way
communications failure should (unless emergency authority is
exercised) comply with 14 CFR Section 91.185 quoted below:

NOTE-
Capitalization, print and examples changed/added for emphasis.

1. General. Unless otherwise authorized by ATC, each pilot who has
two-way radio communications failure when operating under IFR shall
comply with the rules of this section.

2. VFR conditions. If the failure occurs in VFR conditions, or if VFR
conditions are encountered after the failure, each pilot shall
continue the flight under VFR and land as soon as practicable.

NOTE-
This procedure also applies when two-way radio failure occurs while
operating in Class A airspace. The primary objective of this provision
in 14 CFR Section 91.185 is to preclude extended IFR operation by
these aircraft within the ATC system. Pilots should recognize that
operation under these conditions may unnecessarily as well as
adversely affect other users of the airspace, since ATC may be
required to reroute or delay other users in order to protect the
failure aircraft. However, it is not intended that the requirement to
"land as soon as practicable" be construed to mean "as soon as
possible." Pilots retain the prerogative of exercising their best
judgment and are not required to land at an unauthorized airport, at
an airport unsuitable for the type of aircraft flown, or to land only
minutes short of their intended destination.

3. IFR conditions. If the failure occurs in IFR conditions, or if
subparagraph 2 above cannot be complied with, each pilot shall
continue the flight according to the following:

(a) Route.

(1) By the route assigned in the last ATC clearance received;

(2) If being radar vectored, by the direct route from the point of
radio failure to the fix, route, or airway specified in the vector
clearance;

(3) In the absence of an assigned route, by the route that ATC has
advised may be expected in a further clearance; or

(4) In the absence of an assigned route or a route that ATC has
advised may be expected in a further clearance by the route filed in
the flight plan.

(b) Altitude. At the HIGHEST of the following altitudes or flight
levels FOR THE ROUTE SEGMENT BEING FLOWN:

(1) The altitude or flight level assigned in the last ATC clearance
received;

(2) The minimum altitude (converted, if appropriate, to minimum flight
level as prescribed in 14 CFR Section 91.121(c)) for IFR operations;
or

(3) The altitude or flight level ATC has advised may be expected in a
further clearance.

NOTE-
The intent of the rule is that a pilot who has experienced two-way
radio failure should select the appropriate altitude for the
particular route segment being flown and make the necessary altitude
adjustments for subsequent route segments. If the pilot received an
"expect further clearance" containing a higher altitude to expect at a
specified time or fix, maintain the highest of the following altitudes
until that time/fix:
(1) the last assigned altitude; or
(2) the minimum altitude/flight level for IFR operations.
Upon reaching the time/fix specified, the pilot should commence
climbing to the altitude advised to expect. If the radio failure
occurs after the time/fix specified, the altitude to be expected is
not applicable and the pilot should maintain an altitude consistent
with 1 or 2 above. If the pilot receives an "expect further clearance"
containing a lower altitude, the pilot should maintain the highest of
1 or 2 above until that time/fix specified in subparagraph (c) Leave
clearance limit, below.

EXAMPLE-
1. A pilot experiencing two-way radio failure at an assigned altitude
of 7,000 feet is cleared along a direct route which will require a
climb to a minimum IFR altitude of 9,000 feet, should climb to reach
9,000 feet at the time or place where it becomes necessary (see 14 CFR
Section 91.177(b)). Later while proceeding along an airway with an MEA
of 5,000 feet, the pilot would descend to 7,000 feet (the last
assigned altitude), because that altitude is higher than the MEA.

2. A pilot experiencing two-way radio failure while being
progressively descended to lower altitudes to begin an approach is
assigned 2,700 feet until crossing the VOR and then cleared for the
approach. The MOCA along the airway is 2,700 feet and MEA is 4,000
feet. The aircraft is within 22 NM of the VOR. The pilot should remain
at 2,700 feet until crossing the VOR because that altitude is the
minimum IFR altitude for the route segment being flown.

3. The MEA between a and b: 5,000 feet. The MEA between b and c: 5,000
feet. The MEA between c and d: 11,000 feet. The MEA between d and e:
7,000 feet. A pilot had been cleared via a, b, c, d, to e. While
flying between a and b the assigned altitude was 6,000 feet and the
pilot was told to expect a clearance to 8,000 feet at b. Prior to
receiving the higher altitude assignment, the pilot experienced
two-way failure. The pilot would maintain 6,000 to b, then climb to
8,000 feet (the altitude advised to expect). The pilot would maintain
8,000 feet, then climb to 11,000 at c, or prior to c if necessary to
comply with an MCA at c. (14 CFR Section 91.177(b).) Upon reaching d,
the pilot would descend to 8,000 feet (even though the MEA was 7,000
feet), as 8,000 was the highest of the altitude situations stated in
the rule (14 CFR Section 91.185).

(c) Leave clearance limit.

(1) When the clearance limit is a fix from which an approach begins,
commence descent or descent and approach as close as possible to the
expect further clearance time if one has been received, or if one has
not been received, as close as possible to the Estimated Time of
Arrival (ETA) as calculated from the filed or amended (with ATC)
Estimated Time En Route (ETE).

(2) If the clearance limit is not a fix from which an approach begins,
leave the clearance limit at the expect further clearance time if one
has been received, or if none has been received, upon arrival over the
clearance limit, and proceed to a fix from which an approach begins
and commence descent or descent and approach as close as possible to
the estimated time of arrival as calculated from the filed or amended
(with ATC) estimated time en route.

Larry Dighera wrote:
On Wed, 16 Aug 2006 19:19:22 -0700, Sylvain wrote in
:

Larry Dighera wrote:

Please explain how a data link would be useful in controlling an
aircraft that has lost communication capability due to electrical
system failure.

the same way one would for *any* aircraft that has lost communication
capability as described in AIM 6-4-1 for instance?


Please explain how aircraft that has lost (data link and all radio)
communication capability due to electrical system failure will be able
to receive the green 'cleared to land' light gun signal upon arrival
if light guns are eliminated as suggested.

Aircraft wouldn't lose the datalink because it would have a backup
battery. But if it did they could use just one color light and three or
four Morse characters which everyone would be required to memorize.
Every pilot knows S, O, A, and N (even though AN ranges have went where
VOR should have years ago, but I digress) and most people know "V" from
Beethoven's FIFTH-da-da-da-dum.