There is so many matters we have to Jude before predicting in a horoscope. Hope you may use your intelligence before applying my rules in a horoscope.
There is two ways to predict, one via dasha and 2nd by transit. we use both ways.
1) 6th, 8th, 12th and 3rd is bad house. When above house lord is associated with lagan or lagan lord or 4th house lord or venus then during above planet dasha, antardasha or pratyantar dasha , native may facing accidents type situation.
2) Rahu, ketu, saturn, and Mars is associated in horoscope or any of two is associated in horoscope then during own dasha or antardasha or pratyantar dasha native may facing accidents. Specially if they associated in dusthan or 4th house or lagan.
1) If Mars is transit to natal rahu or trine from Rahu.
2) If Mars is transit to natal ketu or trine from ketu.
3)If Rahu is transit to natal Mars or trine from Mars.
4) If Rahu is transit to natal Jupiter or trine from jupiter.
5) If Ketu is transit over natal mars or trine to mars.
6) If Ketu is transit over natal saturn or trine to saturn.
7) Saturn is transit over natal ketu or trine from natal ketu.
8) Jupiter is transit over natal Rahu or trine from Rahu.
9) Sade satti is running.
10) Saturn/mars/rahu/ketu in 6th or 8th from natal moon.
11)When ever 2nd, 7th, 8th house lord is transit 2nd/6th/8th/12th from own natal position then accidents is possible. And mostly accidents happened own that days when moon transit 4th/6th/8th/12th from natal moon. This sutra is given by Y.k.Agrawal sir.
Timing of accidents
When ever both dasha and transit shows accidents then accidents is possible. Accidents may be any type vehicles, fall from heights, cuts, wounds, injuries, fire etc. It is depends on planet and sign significant.