Established on a heading to the field entry-control point, she noticed coaltitude
, converging aircraft on her traffic advisory system (TAS).
As shown in figure 1, the sides are named as follows: (a) Polar Distance, the angular distance between the Pole and the position on earth directly below the star (90 |degrees~ altitude) called the Geographical Position (G.P.), whose latitude remains constant as the star transits the sky from rising to setting; (b) the Colatitude, the angular distance between the Pole and the observer's meridian position; and (c) the Coaltitude, the angular distance between the observer and the Geographical Position.
The greater the diameter of the circle, the lower the altitude of the star, for as mentioned earlier the great circle distance from observer to Geographical Position in angular units gives the coaltitude (90 |degrees~ -- altitude).
There was good reason to select a low altitude (10 |degrees~ -- 20 |degrees~), since this would give him a larger circle whose radius is the coaltitude. A small radius would restrict his measurements to a small range of latitude and involve the greater imprecision of measuring high altitudes.
About 90 degrees through the break, I spotted an SH-60 in an apparent hover and coaltitude with us.
Seeing an aircraft coaltitude that close was not something either of us expected, so it took us a second to process our next action.
I couldn't register the single piece of critical information out there: We had coaltitude
, opposing traffic closing on our position.
With the perceived knowledge that our only coaltitude
traffic was the section of Rhinos far ahead of us, and with our lead behind us, we settled into our routine.
The MC-130 flight lead reported he did not see Tiger 05 at their 1 o-clock and coaltitude
I then saw my wingman at my 9 o'clock, one-half mile, coaltitude
. Did we just hit each other?
After a lot of straining to see around the "Grumman iron," the pilot called "visual" and added it looked like it was "coaltitude
." He then climbed--good thing, too, because before I knew it, we were in a right-to-right pass with a C-130.