I always found that flying a 150 was like sitting inside a mail box looking out through the mail slot, unlike our little Champs in which one sits almost in front of the wing thus avoiding this "tunnel vision" feeling. After a series of frights going into a field in Canada which has dozens of non English speaking of shore students we fited a Picas to our 421, not as good as a Tcas and only totally acurate at low level when de- presurised, but it does give a bearing and elevation of the target, in haze and poor vis its better than a mark one eyball.