(1) In the paper ‘The Avoidance of Collisions for Newtonian Bodies with Hidden Variables’, by B. D. Bramson (vol. 45, p. 55), equation (4.4) should read:

(2) In the paper ‘Quantitative Estimation of Secondary Surveillance Radar Information, by D. J. A. Weeda, L. P. Ligthart, L. R. Nieuwkerk and B. C. M. van der Klein (vol. 45, pp. 26–35), the first initial of the last-named author was given as D instead of B.

On p. 27 line 22, the phrase ‘scans of 32 plots’ should be replaced by ‘scans of 32 numbers of plots’.

On p. 34, the denominator on the right-hand side of equation (12) should be v(v ± Δv) instead of v(vδv).

On p. 35 line 16, ‘air traffic route 1’ should be replaced by ‘air traffic route i’.