Glenn Schneider
Steward Observatory
University of Arizona

For background information on this unique opportunity: CLICK HERE

Flight Parameters:
  • Ground Speed: 2200 km/hr
  • Aircraft Altitude: 60,000 feet above mean sea level

  • Boundary Conditions/ Constraints:
  • Mid-Eclipse Intercept @ Minimum Umbral Veclocity -> 12:05:50 UT
  • Maximum Solar LOS Horizontal Deviation Angle = +/- 45° -> 11:30:50 UT Intercept
  • No overflight of Angolan Airspace -> Break-off @ 12:35:50 UT (allows CIII heading realignment) - PROVISIONAL

  • Total Time for Eclipse Run: 4360 seconds    Total Distance for Eclipse Run: 2664.5 km
    (does not include time/distance to/from Tenerife to intercept and return)

  • The scenario presented here is to be considered a design reference.  While a perfectly viable scenario, as is, details may vary after a review by, and discussions with, Concord flight operations.
  • For early planning purposes lunar limb effects have been ignored, and computatiuons performed quantized to the nearest 10 seconds.
  • Astrodymaic computations of the instantaneous topocentric times, positions, velocities, orientation, etc. of the lunar umbra and aircraft positions to define the intercept profile were performed by G. Schneider using proprietary software developed specifically for this purpose from kernal routines which have been used in planning 21 previous total solar eclipse observations.
  • Eclipse elements and circumstances were independently verified by separate calculations performd by Fred Espanak (Goddard Space Flight Center).  Thanks, Fred.
  • Break-off time is provisional, and may have to be adjusted a few minutes earlier to avoid a TBD buffer zone around Angolan airspace.

  • Eclipse Intercept Initiation - Second Contact Run@ 11:26:00 UT

    One hundred seconds before second contact, at 11:26:00 U.T (gold circle), the Concord will complete a heading alignment change to a new heading of 112 degrees.  This will alter its flight vector from its outbound course from Tenerife to prepare for second contact.  Once on this heading the Concorde will fly through the second contact intercept (a distance of 61.6km in 100 seconds, see next panel) to the point of centerline run insertion at 11:30:50 UT (see third panel). A second heading change at that time (90 seconds after second contact to 66.6 degrees) will put the concord on the 1h05m long centerline run.  The 4m50s second contact run should allow ample time to acquire the sun in photographic instruments before second contact. Remaining on this heading for an additional 190s (116.1 km) will allow observation and recording of post-second contact phenomena (edge prominences, chromospheric arc, etc.) before the required heading alignment change.

     AIRCRAFT HEADING:        112 Degrees
     RUN START:              11:26:00 U.T.
     AIRCRAFT LATITUDE:      13.8235S
     AIRCRAFT LONGITUDE:      9.4486W
     TIME TO MID-ECLIPSE: -2390 seconds
     DIST TO MID-ECLIPSE: -1460.6 km
     SHADOW LATITUDE:        14.9267S
     SHADOW LONGITUDE:        9.0833W
     SHADOW WIDTH:          183.7 km
     SOLAR ALTITUDE:         47.8 degrees
     SOLAR AZIMUTH:          25.0 degrees
     AIRCRAFT HEADING:       112.0 degrees
     HOR. LOS ANGLE          +3.0 degrees

    Second Contact @ 11:27:40 UT

    Flying on the approach to centrline injection, to achieve a centerline intercept as shown in the previous panel, the Concord will be flying at a heading of 112 degrees.  This will place the sun nearly "straight out" the window (horizontal LOS angle of +0.3 degrees) for optimal viewing of the Contact II diamond ring (red circle) at 12:27:40.  The aircraft will fly 116.1 km in 190 seconds to reach the centerline intercept (blue circle) at 11:30: 50 U.T.  Shortly before (some tens of seconds TBD) a heading alignment change to 66.6 degrees is required to begin the centerline run.  The details of the heading alignment arc will need to be discussed with flight operations personnel. 

     SECOND CONTACT @ 11:27:40 UT
     AIRCRAFT HEADING:        112 Degrees
     CONTACT II:             11:27:40 U.T.
     AIRCRAFT LATITUDE:      14.0264S
     AIRCRAFT LONGITUDE:      8.9242W
     TIME TO MID-ECLIPSE: -2290 seconds
     DIST TO MID-ECLIPSE: -1399.4 km
     SHADOW LATITUDE:        14.6683S
     SHADOW LONGITUDE:        8.5050W
     SHADOW WIDTH:          184.7 km
     SOLAR ALTITUDE:         48.4 degrees
     SOLAR AZIMUTH:          22.3 degrees
     AIRCRAFT HEADING:       112.0 degrees
     HOR. LOS ANGLE          +0.3 degrees

    Centerline Run Insertion - Completion @ 11:30:50 UT

    The location of the Concorde (blue circle) within the topocentric projection of the umbral shadow at 60,000 feet (black ellipse) is shown at 11:31:00 U.T., 10 seconds after completion of a heading realignment onto the centerline.  The geometric center of figure of the shadow is noted (white dot).  At this instant the shadow velocity is 2358 km/sec and decelerating. Relative to the shadow center the Concorde will move slowly westward for 8 minutes (but remaining in the umbra) when, at 11:39: U.T. the shadow velocity equals that of the aircraft.  At that instant the Moon will appear stationary in the sky.  The Concorde will then begin to overtake the shadow and at 12:05:50 U.T. it will be centrally located within it.
     MID-ECLIPSE INTERCEPT:  12:05:50 U.T,
     CLINE INTERCEPT + 10s:  11:31:00 U.T.
     AIRCRAFT LATITUDE:      14.3923S
     AIRCRAFT LONGITUDE:      7.8734W
     TIME TO MID-ECLIPSE: -2090 seconds
     DIST TO MID-ECLIPSE: -1277.2 km
     SHADOW LATITUDE:        14.1817S
     SHADOW LONGITUDE:        7.3750W
     SHADOW WIDTH:          186.7 km
     SOLAR ALTITUDE:         49.6 degrees
     SOLAR AZIMUTH:          21.6 degrees
     AIRCRAFT HEADING:       66.6 degrees
     HOR. LOS ANGLE         +45.0 degrees

    Centerline Run Summary

    Centerline Run Simulation

    Click on the links to the right to view annimated simulations of the centerline run from insertion at 11:30:50 UT to mid-eclipse intercept at 12:05:50 U.T, and from mid-eclipse intercept to break-off at 12:35:50 U.T.  Here, mid-eclipse refers to the time at which the Concorde is centrally located in the umbra, this is not temporally summetric with the start and and off the centerline run.
    Insertion to Mid-Eclipse Simulation

    Mid-Eclipse to Break-off Simulation

    Centerline Run Termination @ 12:35:50 UT & Third Contact @ 12:38:40 UT

    Because of the prohibition against flying at supersonic speeds over Angolan airspace the Concorde must break off of the centerline run while totality is still in progress.  To assure this condition not be violated a heading alignment maneuver to a new heading of 57.0 degrees will be executed at 12:35:50 (provisional, but see table above for example).  Once on this new course, after 170s (distance 103.9 km) the Concorde will leave the umbra at 12:38:40, and experience third contact with the sun will be "straight out" the sun-side windows. This course will be maintained for 30 seconds before a new heading is entered at pilots discretion to return the Concord to Tenerife.

     THIRD CONTACT @ 12:38:40 UT
     CENTERLINE BREAK-OFF :  12:35:50 UT
     NEW AIRCRAFT HEADING:    39 Degrees
     CONTACT III:            12:38:40 U.T.
     AIRCRAFT LATITUDE:       10.4792S
     AIRCRAFT LONGITUDE:      14.2415E
     TIME TO MID-ECLIPSE: +1970 seconds
     DIST TO MID-ECLIPSE: +1203.9 km
     SHADOW LATITUDE:        11.0350S
     SHADOW LONGITUDE:       13.7883E
     SHADOW WIDTH:          192.7 km
     SOLAR ALTITUDE:         48.8 degrees
     SOLAR AZIMUTH:          327.0 degrees
     AIRCRAFT HEADING:       57.0 degrees
     HOR. LOS ANGLE          +0.0 degrees

    ALTERNATE SCENARIO - Long Duration CIII Diamond Ring

    A variation on the above theme with a planned mid-eclipse intercept a few minutes earlier (toward the west) can give rise to a contact 3 diamond ring of exceptionally long duration.  Indeed, the duration of the CIII diamond ring can be tailored as desired, but traded off against time fully within the umbra.  In designing such a plan we are still constrained by a viewing angle not to exceed 45 degrees from horizontal, and no intrusion of Angolan airspace.  No graphics have been generated for this yet, but one proposition for a 4 minute long diamond ring is explained here.

    A) Intercept centerline at ~ 11:30:50 as before, BUT with the aircraft slightly further down track (NE) at Latitude = 14.3520S, Longitude = 7.7787W. This is for a mid-eclipse intercept at 12:01:30UT (i.e., 1840 seconds, and 1124.4km after insertion onto centerline).

    B) For a short while, as the shadow is moving faster than the aircraft, the Concorde will move westward with respect to the moving center of the shadow, but remain fully emmersed, until the umbral velocity drops to 2200 km/hour.

    C) Mid-eclipse occurs at 12:01:30 with the aircraft and center of figure of the moon's shadow co-located at Latitude = 11.2550S, Longitude = 2.0833E, with the LOS to the sun +7.3 degrees and an altitude of 55.2 degrees.

    D) Following this the aircraft, still overtaking the umbra begins to approach the edge of the shadow.

    E) At ~ 12:28:50 U.T. the concord should decelerate from 2200 km./hr to 2131 km/hr over 10 seconds to reach this reduced speed at 12:29:00 U.T.

    F) At 12:29:00 U.T., the aircraft will be at Longitude = 11.2987E, Latitude = 10.7717S (1650 seconds, and 1008.3 km, past mid-eclipse) and will experience third
    contact while co-moving at exactly the velocity of the umbral shadow.  At a heading of 93.6 degrees the diamond ring will be "frozen" in the sky.

    G) From this point the topocentric lunar velocity will increase to 2199.3 km/second over the next 4 minutes (at 12:33:00 UT).  By slowly increasing the aircraft ground speed by 68 km/hour over this 4 minute period the diamond ring will continue to remain frozen in the sky.

    F) We can then continue on track for another two minutes until 12:35:00 UT before executing a heading alignment maneuver to return to Tenerife.  At that time we will still be comfortably clear of the Angolan coast by ~ 150 km.