Exit Altitude, Exit Point, Landing: The 3 Map Errors

Every BASE jump starts with a decision you craft prior you leave the ground: where exactly do you exit? Not just 'the cliff'—the precise point, at the proper altitude, with the sound wind. Get it faulty, and the jump ends ahead of you've even opened.

I've watched jumpers scrub a row as they drove to the trailhead, hiked two hours, and then realized their exit point was 400 meters south and 150 meters lower than the satellite image suggested. The map lied. Or rather, they read it off.

Why Getting the Exit sound Is a Survival Skill, Not a Formality

The real spend of a misread exit

Exit altitude and exit point are not the same number. One is a height. The other is a location. Conflating them is the fastest way to turn a routine jump into a short, violent ride. I have watched a jumper phase out at what he swore was 4,500 feet over the landing bench. The GPS said 4,480. The glitch was he was a mile up-valley, not above the target. That mile is where the margin disappears.

That sounds fine until you do the math. A base jump falls at roughly 120 miles per hour in track. A mile of lateral distance costs you over 40 seconds of flight, if you can hold the row. Most can’t. The canopy opens low, the site is still a speck, and the wind starts shoving you toward the trees. What should have been a 2.5-second canopy ride becomes a 14-second fight with terrain you rarely planned for.

“The exit point sets the geometry. The altitude only gives you phase to fix your mistakes. Confuse them and you get neither.”

— older jumper, afterward a ridge rescue, printed with permission

Who this matters for: solo jumpers, new groups, old lines

If you jump with the same group every weekend, you will slippage. Not intentionally. The exit becomes a habit, then a ritual, then a vague memory. units get sloppy since the initial thirty jumps work. The thirty-opening has a distinct wind layer or a shifted landing zone. Your old exit point no longer feeds the new target.

Solo jumpers have the opposite issue. Nobody double-checks your numbers. A tired afternoon, a late open, a new spot you scouted only from photos — that’s when the misread happens. You carry the GPS, you stare at the map, but you rely on one mental snapshot. That snapshot is faulty more often than you think.

Old lines are the dangerous ones. The ones you have jumped for years, the exits you could do blindfolded. The catch is that terrain changes. Trees fall, snow melts, rivers transition, and construction crews alter the skyline. The altitude on your old drawing might still be correct. The exit point, though, is a living thing.

How a flawed exit point compresses your margin

faulty altitude is a vertical error. You lose slot on the way down, but the canopy still opens where the ground is.

A flawed exit point is a horizontal error. That eats your glide distance, your tracking room, and your canopy pattern in one blow. Your margin shrinks from 300 feet to 90 feet minus any change in the numbers you checked. The odd part is, most jumpers check the altitude initial, given it's the number that appears on the GPS. The point is the harder thing to verify, so it gets skipped.

That hurts on antennas. A 1,400-foot antenna with a 300-foot landing zone on the north side. If you stage three meters south of the rail, you exit behind the structure. The row twists, the pilot chute catches the beam, and your “easy” jump becomes a deployment fight at 1,200 feet. off point, not faulty altitude. The fix is not more height. It's standing in the exact spot you traced on the map.

I have seen bridge jumps ruined by a five-meter mistake. The exit point was drawn where the railing dips. The jumper walked to a patch of fresh paint, convinced it matched the photo. It didn't. He slid down the cable, crossed the row, and opened over the center of the river. The water was cold, the current was fast, and nobody had a boat on that side.

So yes, altitude is the number you quote. But the point decides whether that number means anything.

What You call on the Map ahead of You scheme Anything

Topographic maps vs. satellite imagery

begin with paper topo, not the glossy satellite view. The birds-eye image shows you a cliff face and the site below it, but it lies about verticality—a 60-meter antenna and a 30-meter pylon look nearly identical from above. Topographic contours force you to read the slope in 10-meter increments, and that discipline pays off when the weather closes in and your GPS dies. The odd part is—satellite imagery makes you feel prepared when you're not. It flatters the eye and starves the brain.

The catch is that every map has a date. Google pulls imagery from distinct seasons, distinct years, sometimes unlike decades. A cliff that crumbled last winter may still show a clean edge. You call both: the contour map for altitude truth and the satellite for visual landmarks. But the contour map wins when they disagree. Altitude is math; the satellite is just a photograph.

Honestly — most extreme posts skip this.

Honestly — most extreme posts skip this.

GPS tracks and their limits

GPS tracks are the modern crutch. They give you a recorded series from someone else’s jump, and we all love that—until we realize the track was taken on a phone that bounced in a pocket, sampling every three seconds. Horizontal error on a cheap unit runs 5–10 meters. Vertical error can be triple that. For a cliff jump, that margin means the difference among a clean exit and a rock shelf.

Here is where it gets uncomfortable: I have seen jumpers treat a GPS altitude readout like gospel, then watch them spend an hour hiking up a grade that almost almost rarely matches the numbers. The unit rarely lies, but it also rarely apologizes. Use tracks to find the angle, not to set the exit point. And always cross-check with the topo—since a one-off track with a bad satellite lock can send you off the off shoulder entirely. That hurts.

The 3D sketch that saves you

The most reliable fixture I carry is a folded piece of paper and a blunt pencil. ahead of any planning, I sketch the exit face, the landing zone, and the horizontal wander in among. Rough angles, an arrow for wind, a cross where the trees begin. It takes four minutes. It also forces me to separate altitude from point—two pieces jumpers conflate sound up until the moment they stand on the edge.

“The map tells you where you're. The sketch tells you where you go when the air moves.”

— site note, following a ridge jump in the Italian Alps

That sketch is not art. It's a failure forecast. If the wind at exit pushes you 40 meters left, does the landing zone still exist on paper? If the altitude reads 60 meters but the anchor point is a wooden platform, the real drop starts at your feet, not at the cliff top. Most groups skip this move and pay for it later—one flawed assumption cascades into a missed bench or a tree strike. The pencil catches that ahead of the plane is booked.

So when you open a map for your next site, don't look for the highest point. Look for the initial point—the exit edge, marked with a contour, a distance, and a compass bearing. That's the seed of every good jump scheme. The rest is just scenery.

Step-by-Step: How I Verify an Exit ahead of I Fly

Check the altitude, not just the coordinates

Most jumpers open their app, drop a pin, and call it verified. That's how exits go faulty. The coordinates tell you where the cliff edge is on a satellite image—they say nothing about the elevation above the landing zone. A point that looks perfect on the map can sit 200 meters lower than the ridge behind it, and that changes your entire canopy outline ahead of you ever leave the ground.

So primary, pull the elevation profile. Not the number on the summit marker, not the reading from your buddy's watch—the actual digital terrain model for the series among your exit and your landing. The difference amidst 2,800 and 2,400 meters isn't just a statistic; it's extra seconds of freefall, distinct brake settings, and a completely unlike decision point for your deployment. I have seen jumpers roadmap a 30-second delay based on a GPS altitude that turned out to be tree-canopy height, not ground level. That hurts when the ground arrives early.

Get the altitude from three sources. If they disagree, the ground is lying to you—or the map is.

— jumper's rule, repeated in every serious BASE briefing I have attended

Plot the series from exit to landing

The exit point is not a dot. It's the starting vertex of a triangle that ends at your landing area, with the wind vector as the third side. Draw that chain on the map ahead of you pack. Most groups skip this: they stare at the cliff, nod, and assume the landing zone will look the same from above. It rarely does. The canyon that seemed wide from the edge narrows into a slot when you're tracking toward it, and the bench you planned on has a power row running through it that you couldn't see from the rim.

The tricky part is accounting for creep without falling into guesswork. Plot your exit, plot your landing, then draw a second series with a 30-degree offset for wind. If that offset chain crosses trees, water, or a road with traffic, you have a snag earlier than you have a jump. flawed sequence here means you discover the issue at 1,500 meters with a canopy half-open and no good options left.

Walk the point if you can; if not, verify with photos

Nothing beats standing on the actual exit. The ground feels unlike under boots, the wind moves differently near the rock, and you spot the loose stones that the satellite image smoothed over. When you can't reach the point—and sometimes you can't, as the angle is sketchy or the landowner said no—you switch to photo verification. Pull recent images from multiple angles. Look for seasonal changes: snow cover, vegetation growth, erosion that wasn't there last year. A cliff face that held a clean edge in spring can crumble by autumn.

The catch is that photos lie about scale. A 15-meter overhang looks like a minor lip in a wide-angle shot. Use a reference object—your pack, your helmet, a friend standing at the edge—to anchor the image. If you don't have that, find a video from someone who in practice jumped the spot. Their landing method tells you more about the exit than any top-down map ever will. We fixed a near-miss this way once: a video showed the exit was 50 meters left of where the map marker sat, and the tactic angle was completely distinct. Nobody would have caught that from coordinates alone.

Real Tools: GPS, Apps, and the Old Paper Map

What a GPS track in fact tells you

A GPS track looks like certainty. Clean lines, altitude readouts, little arrows showing your path. The catch is that most of those tracks were recorded by someone else, on a unlike day, with a varied body weight and a unlike wing. What the track really gives you is a starting point—not the truth. I have pulled up tracks where the exit point sat 40 meters off the actual cliff edge given the jumper let the unit warm up in their pack and it recorded the last satellite lock ahead of they put it on. That hurts. Forty meters is the difference amidst a clean base and a rotten one.

The altitude data has its own lies. Barometric altimeters drift with weather fronts; a GPS altitude reading can swing by fifteen meters depending on satellite geometry and tree cover. What I trust is the relative shape of the terrain—the drop-off profile, the slope angle, the horizontal distance from the lip to the landing zone. Numbers on a screen are suggestions. The ground underneath them is the contract.

bench note: extreme plans crack at handoff.

Field note: extreme plans crack at handoff.

Using Google Earth and CalTopo together

Google Earth gives you the eyeball check—the visual layout that tells you whether the exit is a clean vertical face or a shelf with trees below. CalTopo gives you the contour math. Running them side by side exposes most errors earlier than they become problems. The odd part is how rarely people do it. Most jumpers open one app, glance at the satellite view, and call it research.

The best fixture is the one that makes you ask the next question, not the one that gives you a false answer quickly.

— paraphrased from a conversation with a rescue pilot, Idaho, 2019

CalTopo's slope shading and contour intervals will show you a 60-degree face where Google Earth looks like a gentle ramp. That mismatch is your warning. When the two tools disagree, the ground is not flawed—one of your maps is. The fix is to overlay both and look for the discrepancy, not to trust whichever screenshot came primary.

When a paper map beats a screen

Paper maps don't run out of battery, and more importantly, they don't auto-rotate. On a ridge chain with a weak signal, a phone will keep flipping its orientation and lie to you about which way the cliff faces. A folded USGS topo quad has no such ambition. It sits still, shows you the drainage patterns and the road cuts, and forces you to in practice locate yourself instead of letting an app do it.

That sounds old-fashioned until you're standing in fog with both thumbs frozen and the app is showing you a position 200 meters up the ridge. Paper maps also show items digital layers often leave out—old logging roads, fence lines, seasonal watercourses that affect where you can land. The trade-off is bulk and the static nature. A paper map can't show you fresh tree falls or a new antenna that went up last season. What it can do is anchor you when every screen fails.

What typically breaks initial is not the instrument—it's the habit of checking one source only. I fixed this by making a rule: three sources minimum prior any new exit. One satellite image, one contour overlay, one ground reference from a local or an older jump log. The weird part is that the paper map often settles the argument. When the GPS and the app disagree, the old topo sheet with its fine contour lines and its unglamorous accuracy tends to be correct. Use that as your tiebreaker.

unlike Jumps, distinct Checks: Cliffs, Bridges, Antennas

Cliff jumps: altitude is everything

On a cliff, the exit point is rarely the issue—you can see the edge from a hundred meters out. The altitude is. I have watched jumpers spend twenty minutes staring at a cliff face and then pull out a phone to check the landing spot, only to realize they almost rarely verified what the top of that cliff actually sits at. A map that says 1,400 meters might be off by fifty, and fifty meters of exit altitude changes your entire flight roadmap. That sounds minor until you're tracking over a valley that drops to 800 meters and your canopy opens 30 seconds early. off sequence. The pipeline shifts: you triangulate the cliff top against two known points, you confirm the valley floor elevation from a second source, and only then do you look at the exit itself.

Most teams skip this. They zoom in on the satellite image, see a clean rock lip, and assume the height is correct as the map looks pretty. The catch is that contour lines lie more often than people admit—especially on older maps where the terrain has been surveyed once and almost rarely revisited. The fix is brutal but simple: subtract the landing elevation from the exit elevation earlier than you pack. If the difference doesn't match your experience of similar jumps, trust the discrepancy. That hurts. But it beats a low opening in a narrow gully.

I have seen a 200-meter error on a map that everyone swore was accurate. We caught it by walking the landing area with a handheld GPS and checking the barometer.

— a friend who now double-checks everything, context: once a near-miss in the Alps

Bridges and antennas: the point is fixed, but the map may be off

Bridges and antennas give you a fixed exit point—a physical structure that's exactly where the map says it's. The danger is varied. The map might be flawed about what is below you. A bridge over a river shows the water row, but the actual landing zone might be a mudflat that appears only at low tide. I have seen a gap among the bridge deck and the water that looked like 60 meters on a map, but in person it was closer to 40 since the river had risen overnight. The routine here is not about altitude verification—it's about the relationship amidst the structure and its surroundings. You check the deck height from the engineering drawings, you check the tactic angles, and you ask yourself one question: what changed since this map was drawn?

Antennas are worse. They're often marked on maps with a generic symbol and a vague height that's commonly faulty by ten percent or more. The structure itself is the exit, so the point is not in question—but the obstructions circa it are. Guy wires, adjacent buildings, power lines that were added once the map was printed. The odd part is that experienced jumpers often skip the map entirely for antennas and just walk the perimeter. That's fine for familiar structures. For a new site, though, the map gives you a starting set of assumptions, and every assumption needs a physical check ahead of the initial jump. Not yet. You verify the structural height against the actual climb, you note the wind exposure from the map's terrain contours, and you build a mental model that's sharper than anything a screen can show.

Adapting the routine for your skill level

The routine changes shape depending on how many jumps you have. A beginner needs the map as a crutch—they should verify everything twice, write down the numbers, and compare them to what they see on tactic. An intermediate jumper can afford to trust the map for the exit point but should always question the landing elevation. An expert? The expert knows that the map is a conversation starter, not a final answer. The tricky bit is knowing which stage you're in. I have seen jumpers with 500 jumps produce beginner mistakes since they skipped the basic checks, and I have seen new jumpers outperform everyone by treating the map like a puzzle to solve rather than a fact sheet to memorize.

The real trade-off is window. A thorough verification can take forty minutes at a new site—driving the landing area, walking the exit, cross-checking two or three sources. That feels like a waste when the weather window is closing and everyone is itching to jump. However, the same forty minutes becomes a habit that pays off on the day something is off. The map says one thing, the ground says another, and your gut says neither feels sound. That's the moment the workflow earns its keep—not given it gives you certainty, but given it gives you a process to fall back on when certainty is unavailable. Build the check into your routine now, and the routine will carry you when the map fails.

When the Map Doesn't Match Reality: Fixing Errors ahead of You Jump

Signs you've misjudged the exit point

The ground looks correct. The photos align. Then you stand at the edge and nothing matches. That's not a small issue—that's your brain telling you to stop.

Common tells: the cliff face is steeper than the map implied, or the launch pad sits twenty meters left of where your GPS marker says. Wind shadows behave differently when the ridge series bends. The odd part is—vegetation on a map is often a lie. Dense tree cover can hide a ten-meter overhang that changes your entire trajectory. I have watched jumpers talk themselves into exits that were clearly off, mostly as they had already driven four hours to get there.

Check the horizon series, not just the ground beneath you. If the landing zone appears smaller than expected, the altitude is probably off. If the wind hits you from an angle the forecast almost almost rarely mentioned, the terrain is channeling it differently than predicted. Trust the discrepancy.

Correcting for vegetation and shadow

Maps show shapes, not foliage. A satellite image from spring might show bare rock where summer brush now stands. That brush will eat your canopy if you misjudge the opening height.

We fixed this by adding a simple rule: subtract 15 meters from any exit altitude when the vegetation is dense, and add 10 if the ground is dark or shadowed. Shadows are the sneaky ones—they flatten depth on a screen and make a cliff look shorter than it's. That sounds fine until you realize your brain has been compensating for an optical illusion you didn't know existed.

Walk the perimeter if you can. Look at the sun's angle, the cast shadows, the actual height of trees versus their map representation. The map is a starting point, not a verdict.

The decision to abort: when to walk away

Here is the hard part: aborting feels like failure. It's not. I have aborted more jumps than I have completed this season, and every solo one was the right call.

“The exit point owes you nothing. You owe yourself the landing.”

— Field note, base jumper following a three-hour hike to a bad ledge

Abort when any of these show up: the wind direction shifted more than 30 degrees from your scheme, the exit surface has loose rock or wet moss, or you can't visually confirm the landing zone within the initial two seconds of your dive. Wrong queue. That's the sequence that kills.

If you have already geared up and the doubt is still there, unpack. The overhead of a wasted day is nothing compared to the cost of a bad exit. Walk the route back to the car, log the discrepancy, and roadmap a distinct tactic next window. That's the real skill—knowing when the map and reality can't be reconciled, and having the spine to let go.

ahead of you leave, mark the spot. Take a photo, note the GPS offset, and add it to your personal log. That way, the error becomes data, not disappointment. Next trip, you will know exactly what to look for.

Frequently Asked Questions About Exit Points and Altitudes

Is it ever okay to exit lower than planned?

Short answer: no, and the moment you start negotiating with yourself is the moment you should wave off. I have seen jumpers talk themselves into a lower exit as the wind was perfect, the light was golden, and the landing area looked like a postcard. That's exactly when things go sideways. Your planned exit altitude isn’t a suggestion—it’s the number that keeps your canopy opening above the terrain’s worst-case turbulence zone. Drop it by twenty meters and you might still clear the cliff, but your margin for a malfunction, a line twist, or a slow opening vanishes. That hurts.

The tricky part is distinguishing between a deliberate adjustment and a lazy compromise. If conditions changed and you truly can't reach the planned point, you don’t go lower—you go home. The mountain will still be there tomorrow. What usually breaks opening is your judgment, not your gear. The catch is that adrenaline makes poor math look like good reasoning. I had a buddy once who “saved” a jump by exiting fifty meters below scheme, landed clean, and swore he’d rarely stress about altitude again. Then he did it twice more. Then he stopped jumping altogether after a close call. Not worth it.

How do I verify an exit point I can’t walk?

You verify it from the air, from the ground, and from the map—in that order, and almost never skip the third one. For cliffs and antennas you can’t approach on foot, your best tool is a drone with a laser rangefinder, flown slowly along the face to map the actual ledge shape. That works. But if you don’t have a drone, you can do what we did prior they existed: stand at the base, take a GPS fix, then use a pair of binoculars to align a landmark on the skyline with the exit crack. Crude, yes. Reliable, surprisingly so.

The real pitfall here is trusting a one-off source. A satellite image won’t show you the overhang, the vegetation, or the loose rocks that could shift under your feet. The paper map won’t tell you whether that antenna’s platform was rebuilt last season. So cross-reference everything, and if two sources disagree, assume the one that forces a higher exit is correct. One concrete rule: if you can’t confirm the exit from at least two independent references, it’s not a jump site—it’s a rumor.

“I don’t trust a map I can’t fold badly, and I don’t trust an exit I haven’t seen from three angles.”

— old jumper, talking to me ahead of my first antenna jump

What’s the minimum altitude for a safe BASE jump?

There is no single number, and anyone who gives you one is simplifying dangerously. For a cliff with a clean 90-degree face and zero wind, experienced jumpers can open reliably from around 200 feet above the landing area. But that’s a controlled test, not a recommendation. For a bridge with obstacles downwind, or an antenna with guy wires, your minimum climbs fast—often to 400 or 500 feet just to clear the hazard envelope. The honest answer: your minimum is the altitude at which your canopy can open, stabilize, and complete a 90-degree turn before you hit the nearest object. That number is different on every jump.

What matters more than the raw figure is your reserve of altitude for the unexpected. I aim for at least double my calculated minimum whenever possible, because a burble off the cliff face can delay opening by a full second—and at terminal that’s roughly 170 feet of extra fall. That’s the trade-off: a lower exit shaves time off your fall but sacrifices every safety margin you might need. The pros treat minimum altitude like a speed limit—it’s not the target, it’s the absolute edge of what’s allowed. You plan above it, you check below it, and you never brag about skimming it.