TALK of the dizzy heights of success to top Canada-based rider Dave Penna and it can have a very different meaning for the likeable jockey who is here on a three-month international licence. Penna, born in America but a multi-million dollar earner on the Canadian circuit, has been at the top for a long time but it could all have been very different back in 1986. It was very late in the previous year when Penna was involved in a car accident which put his whole future career in jeopardy . . . not so much from any physical injuries which resulted from the smash. Instead Penna discovered he was suffering from vertigo - a word pitched into the popular vocabulary by the Alfred Hitchcock thriller of the same name. A paralysing dread of heights is not exactly ideal for a jockey and Penna missed virtually all of 1986 as he underwent a long drawn out rehabilitation stint to rid him of the affliction. ''It was not something you ever want to go through again. It was totally alien to me and came about directly as a result of the car crash. It was touch and go for some time but the rehab people were excellent. ''But it took almost a year out of my career and sometimes it's hard to get back. Fortunately, I had done well enough before the crash and I was able to more or less carry on from where I left off,'' he said. In fact, it was post-crash that Penna's career really took off in Canada. In 1987, he had a golden year, winning 20 Stakes races and guiding a top galloper called Regal Classic to a thrilling second-place finish in the Breeders' Cup Juvenile. ''That's one I would dearly have loved to win,'' he still reflects. It all began for Penna in Auburn, New York on January 11, 1959 and he made his debut in 1978, showing a quick aptitude for the skills necessary to make it to the top by riding 31 winners in his first season. Although riding in and around New York, he was lured to Ontario by one of the all-time greats of racing in that part of the world, the late Hall of Fame trainer, Frank Merrill. It was a move that made Penna a household name in Canada and then in the warmer climes of Calder and Gulfstream Park in Florida during the northern winter. ''It worked out really good and I have made my base there ever since,'' he says. So good, in fact, that Penna is one of only three jockeys to have broken the US$3 million mark in career earnings in a season. His total stakemoney earnings up to mid-August are just on the US$30 million mark. He has been leading rider in Ontario for several seasons and, before coming to Hong Kong for last April's International races, had landed 95 wins including successes on the top galloper King Corrie in the Toronto Budweiser Breeders' Cup and the HighlanderStakes. He finished the season as the leading rider at the internationally known Woodbine track, scoring 22 times which was double that of his nearest rival, Sandy Hawley. The quick trip to Hong Kong for the International races whetted his appetite for more of the Far East and, when the Jockey Club were seeking an American rider to start the new season, Penna was quick to agree. But it has only been in the last 10 days that his Hong Kong stint has tended to take off - and particularly so with his link-up this week with Patrick Biancone. And he has been in trouble with the stewards over use of the whip - something of a sore point with him, never mind the horses. ''I am in a difficult position. Here I am trying to do my best on horses that aren't really good enough to win - but I want to show trainers that I know my business. ''So I am really persevering on horses and maybe getting them to go that bit better so that, next time, I'm on something decent. At one stage I thought the fines were going to be more than my riding fees!'' But Penna has struck the right chord with some trainers here - not least Lawrie Fownes. It was Fownes who handed Penna his breakthrough winner when Blazing Blade saluted two weeks ago. ''He's a good boy and a good rider. I was delighted to put the horse his way and he did the rest,'' said Fownes, who has a home in Canada and was well acquainted with Penna's exploits on the turf over there. Penna's open, easy-going personality has made him popular during the daily Sha Tin morning routines and he has slowly but surely impressed good judges with his ability. ''It's hard when you're trying to do it on horses that can't win. It does make it a relief when you get on one that can and sort of show people that you do know what this game is about,'' says Penna. His surprise link-up with Biancone should pay dividends over the next few meetings and he is certainly in demand today with seven rides on the eight-event programme. Fines for whip abuse, unfit horses and downright rogues . . . it's not exactly been a bundle of laughs for Penna since mid-September. But you wouldn't know that by talking to him. And with Dave Penna, it's definitely not a case of good guys finishing last.