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21.  It is obvious therefore that DME fixing is more accurate than CRDF.
In addition, DME fixes are instantaneous, whereas if a leader has to resort
to CRDF fixing, the bearings obtained by his No. 2 may be several seconds
old when he needs them, giving rise to even larger errors.

22.  Although DME/DME is the most accurate, beacon selection must be
carefully made since only 90 degree cuts give minimum errors, e.g.

     at 100 n.m.  90 degrees cut - maximum error 2 n.m.

                  120 degree cut - maximum error 3½ n.m.

                  150 degree cut - maximum error 7 n.m.
                  
                  180 degree cut - maximum error 20 n.m.

All these are instrument errors above and do not include plotting errors.

Some Operating Hints.

23.  The keyword in making a successful interception under Broadcast Control
is ORGANISATION. The following points will all help to make sure you intercept
your target.

     (a)  Fly with your DME at Standby at all times when you don't require
     it. It takes 20 minutes for DME to reach maximum efficiency. Until
     this time period has elapsed, even though you may get a "look-on",
     readings may be less accurate than ±2%. Don't switch from "OFF" to
     "200" without first warming up on Stndby. It will eventually ruin
     the valves.

     (b)  Start plotting as soon as possible and establish an intercept
     vector. Fly as smoothly as possible. Frequent turns will tend to
     unlock your DME.

     (c)  Hold a steady interception speed.

     (d)  Get height advantage over the target, so that it will appear on or
     near the horizon. (2000 ft. at 5 n.m., 4000 ft. at 10 n.m. etc.-)

     (e)  Fly your No. 2 in a position to give both manoeuvrability and
     search and feed him with information on target position and range, so
     that he can use his search to maximum benefit.

     (f)  In all cases except near head-on go directly towards the estimated
     interception point. Trying to set up fancy interception patterns will
     usually lead to errors and long tail chases.

     (g)  Keep the plot going right up to the point of collision.

     (h)  Don't rush off after any likely looking contrail. Chock first from
     your plotting board that it is in the correct relative position to yourself,
     and keep your plot going to confirm this.

     (j)  If No. 2 sees target first he should go to the Broadcast frequency,
     call out your mission Number and return immediately to the natter frequency.
     No. 1. should follow to the natter frequency and target reporting and then
     be called.

2.   Broadcast control interceptions call for a great amount of skill. Practice
is the only way of becoming proficient.

                                                       /Green Salad.

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