I often fly the Boeing 737 and the Boeing 777, and I often try landing at speeds of 155-157 knots for both planes.

I assume you fly the 737-400.Depeding on the weight, at Flaps30 the Vref is appr. between 120-155 ktsUnless you have a very high landing weight, 155 is way too fast. A medium weighted 400 has a Vref on appr. 135kts, so your appraoch speed will be around 140kts like WhiteKnight indicated.The same apply for the 777-200 BTW...Vref25 at 150T: 123kts / Vref25 at 250T: 159ktsA medium weighted 777-200 at 200T has a Vref25 of 142kts

If you're diving at the runway, it would suggest that you are going above the G/P or PAPIs/VASIs in the latter stages of the approach and /or you are flaring too early. Even at a too high a speed, you shouldn't need to dive at the runway if your flare is correct. It just means that you will float further down the runway as your speed bleeds off to the correct speed for your weight if you hold the correct landing attitude and the aircraft can then settle on the runway.Colin B

A few pointers:For ease of practice, try the 737 with about 5,000lbs of fuel for the approach.-Setup an approach 10 miles from the runway at 3,000ft above the touchdown zone elevation (e.g. TDZE=1,000ft then start at 4,000ft). This should give you plenty of room to make mistakes.-A good rule of thumb for how high you should be at any point along the approach is 300 ft of altitude/nautical mile for a 3 degree glideslope-fairly typical-Start the approach practice with gear down, flaps 40, and 145 kts IAS-Practice with no weather to begin with-Tune the ILS for reference but hand-fly if desired-In this configuration your nose should be a degree or two above the horizon -At approach speed and no wind, you can expect to descend at 700ft/min-Ideally, you want to find a trimmed pitch (degrees nose up) and power (N1) configuration that has you descending in the landing config at 700 ft/min at 145IAS. When you finally find this, remember it, and you can use it on every approach that you fly. You will have to make fine adjustments, but this is the best place to start! (This is most easily accomplished by setting the autopilot and observing the aircraft behavior)Once you get close to the runway and are on glideslope you should see the PAPI lights...you want 2 red/2 white. Tune VS as appropriate. Once you have the touchdown markers in site (the two big squares 1,000 ft down the runway) then visually focus on and aim for those. They should stay steady in your view (i.e. not moving up/down/left/right). At 50 ft, transition your viewpoint 3/4 of the way down the runway for better flare depth perception. At 30 feet gradually move the nose up a few degrees (you won't need too much to slow your descent) and fly the plane nicely onto the runway. At around 20 feet, retard the throttles smoothly to idle.Spoilers, brakes, and reverse to get you stopped. As everyone else has said...practice, practice, practice.Hope the helps.

Apart from Vref as previously mentioned ATC (that is the real ATC) will give you speed advisories both for final approach and SARs. In the case of SARs speeds may be published.Assuming then that you are at say FL70 and 30DME from your destination:-You must not be above 250IAS and in fact probably slowing down to 210IASMake your descent to 3,000 or 2,500 depending on the terrain and ATC at 210IAS (This may involve partial extention of speed brakes)As you turn to establish on the localiser you should be at 180 or 170IAS with first stage flaps depending on traffic.At about 6 or 7DME drop your gear and extend the flaps one or more settings (dependant on the a/c)As you cross the outer marker slow down to about 140IAS and extend full flapsAt screen height begin to flare thus allowing the a/c to settle back to Vref as it touches down.If your Vref is above 140IAS then you are probably too heavy and need to dump fuel over the ocean!!!Easy!!Vololiberista

Also, to start getting technical, once you begin your approach say 10 miles backat say 3200 feet, onve you intercept the glideslope, another rule of thumb is to take your groundspeed, divide it by 2 then add a zero at the end and that would be your vertical speed you want to acheive, this is very easy to do and extremely accurate.Example, say you groundspeed is 120 knots, you divide 120 in 2 and you get 60, now add a 0 to 60 which gives you 600, and voila, that is what you should try to hold on your descent on your vsi, but remember you have to be on glideslope for this to work.For me this is extremly accurate, and always, and I mean always works out for me, in any aircraft.

there are alot of videos on youtube that can help you!