Despite the advances in other areas, Airbus lagged behind when it came to wingtip devices. The conventional and all too familiar wingtip fences that we see on the Airbus A300s, A310s, A320s and the A380s did their job, but a scope for improvement always existed. The Airbus A330s and the A340s broke from the norm by employing conventional winglets, similar to the ones seen on a Boeing 747-400.
On the 30th of November 2011, when the first ever A320 to be produced: MSN 0001 took to the skies, this wingtip complacency was relegated to a page in history. With the first flight of an A320 with “Sharklets”, the Airbus lingo for winglets, Airbus was ready to give to the world a much awaited confirmation and assurance of a winglet that will finally make its way to production aircraft.
Vortices which result at the tips of wings as a result of the pressure difference that exists between the upper and lower surfaces of the wings induce a drag which reduces the wing’s aerodynamic efficiency. Winglets are small , nearly vertical aerodynamic surfaces which are designed to be mounted at the tips of aircraft wings. A properly designed winglet impedes these vortices, shifting them instead further up to the tip of the winglet, resulting in much weaker vortices. As a result, the induced drag is significantly reduced, improving the lift to drag ratio of the new compound wing structure.
An increased lift to drag ratio implies lesser engine thrust requirement for a desired amount of lift, which directly relates to fuel savings. Like other winglets, these Sharklets bring with them a bundle of realistic promises, the biggest of which is a 3.5% fuel saving over 3000NM-long flying sectors, and around 1% fuel saving over 500NM long sectors, in comparison to A320s flying with the conventional wingtip fences.
For an A320 operator like Indigo, which deploys its A320s on a mix of medium haul international and short haul domestic routes, the savings can be huge. Based on the flight schedule, Indigo can comfortably deploy one A320 on the Bangalore-Mumbai-Singapore-Mumbai-Bangalore pattern every day. Fuel cost at Bangalore and Mumbai have been approximated to be the same.
Projected savings on a single A320. Fuel Prices as of Dec 25th, 2011. 3% fuel savings (assumed) used for 2000NM and 1% fuel savings (Airbus data) for 500NM.
With this pattern, the same A320 operating with Sharklets can save about US$400,000 per annum on fuel related costs.
According to John Leahy of Airbus, the price for the winglet will be similar to the forward fit, of around US$950,000, although the retrofit kit could add to the cost, though not substantially. A pair of Sharklets attached to an A320 flying the above pattern can pay back for itself in 2.5 years. Six A320s in Indigo’s fleet (INA-INF) are 5 years old. If Indigo plans to get rid of aircraft around 5 years old, a potential US$ 1M is saved by the airline, per aircraft.
But these are not the only savings. Either the revenue payload can be increased by 500kgs, or the range can be extended by 100NM at the original payload. The increased lift to drag ratio of the wing will result in higher available takeoff weights, notably from obstacle-limited runways, and where runway performance is not limiting, operators could profit from a reduction in average takeoff thrust (with consequent savings in engine maintenance costs by around 2%). The Sharklets lend the aircraft a better takeoff performance and rate-of-climb, higher optimum altitude, higher residual aircraft value, and greater safety margins in the event of an engine failure.
I was asked today by a very good first officer for a “5 star” airline the difference between Minimum Acceleration Height and Maximum Acceleration Height as seen on RTOW charts. For example, the RTOW chart for an A319 with the IAE V2522-A5 engines from Bangalore’s old HAL Airport (VOBG) shows a min and max acceleration height of 436ft and 1333ft, for a departure from runway 09. What does this mean?
Opening Airbus A319 FCOM 2.02.10 describes the acceleration height as that which “ensures that the net flight path clears the highest obstacle by at least 35ft when accelerating in level flight to Green DOT (Maximum lift to drag ratio speed in clean configuration) speed after engine failure, in the most adverse of conditions.” That can only be the minimum acceleration altitude. The acceleration altitude never goes below 400ft. Anything above 400ft is to ensure operational minimum acceleration height.
So what is the maximum acceleration height in that case?
A take off has four segments: First, Second, Third, and Final.
First Segment: from 35ft AGL to Gear Retraction, with takeoff thrust at V2 minimum.
Second Segment: from gear retraction to acceleration height, at V2 minimum, with take off thrust.
Third Segment: from acceleration height to reaching green dot speed. This segment must end at a maximum of 10 minutes from the start of the take off roll.
Final segment: A climb at green dot speed till 1500ft AGL with MCT (Maximum Continuous Thrust).
What determines the maximum acceleration height are the following:
a) A minimum of 1.2% climb gradient when above the acceleration height.
b) Green Dot speed must be reached 10 minutes after starting take off roll.
For this, you must construct the path backward.
1. Determine the time taken for the aircraft to accelerate from V2 to GDOT with a) Single Engine TOGA b) Worst case RTOW c) 1.2% climb gradient. Call this “t1“.
2. Determine the time taken for initiation of take off roll to attaining V2 with one engine failing at V1. (35ft above the ground). Call this “t2“.
3. Determine the time taken for aircraft to completely retract gear, from 35ft above the ground (First Segment). Call this “t3“. The height attained in this first segment may be considered height “h1“. All this is with one engine inoperative, with the other generating TOGA thrust.
4. The time remaining for the second segment is “t4” = (10 – (t1+t2+t3)). 10 minutes is considered as that is the maximum duration for which a single engine may be operated at TOGA. Note that the worst case assumption is for a take off at TOGA, with worst case RTOW (Heaviest), and engine failure at V1. With these parameters of physics, the climb gradient is calculated for the second segment at V2. With the climb gradient, the height attained in time t4 is “h2“.
5. Thus, with the height the aircraft attains, above the ground, at the end of the second segment, with TOGA thrust on one engine, other engine inoperative at V1, and the worst and heaviest weight restricted by the runway, is the maximum acceleration height.
If a pilot attempts to climbout beyond the maximum acceleration height maintaining V2,the live engine may exceed the 10 minute TOGA limit, risking engine failure and consequently total loss of thrust, before the Green Dot Speed is reached.
I also was fascinated by the Jacobson’s flare, “A practical and very tolerant technique for establishing a consistent landing flare that does not rely on the pilot’s perception of vertical height”. This method is slowly gaining popularity for its obvious benefits. You may read more on this on the “official” webpage: http://www.jacobsonflare.com/
This weekend was pretty relaxed, with nothing much taking up my time. The weather was great, and it still is. Saturday evening was made brilliant with a nice lunar eclipse, and a nice ride to the airport to see planes land and pick up my dad.
I am somehow fascinated by Indigo’s culture: when the airline sees something worthwhile, they actually implement it. I heard from an Indigo pilot that they have regular safety information bulletins issued, which touch upon any and every topic that is of interest to flight safety. Some may laugh and most may not read it, but it is there to be read.
The issue of incorrect FMS weight entries has been bothering me. A simple ZFW entry taking the place of TOW or GW can be the simple oversight that may lead to an incident, serious incident, or even an accident. How to safeguard against these errors is something that’s worth pondering on.
Fatigue is probably a contributory factor, and this fatigue needs to somehow be determined. Imagine, if the fatigue of a crew member’s can be gauged, the level of awareness, or oversight can appropriately be increased to prevent errors. Imagine a first officer knowing that his captain is stressed, or fatiugued: he can keep a closer eye on what the captain is doing. But then again: what is both crew members are stressed?
FMS weight entries: Weighing the consequences of simple errors!
Not long after the first flight of the “sharklet” equipped A320 did Airbus go public with the news of it suing Aviation Partners for demanding royalties for the Airbus’s “sharklets“.
The sharklets are very similar to the patented blended winglet design of Aviation Partners Inc. Infact, Airbus in 2009 was evaluating the Aviation Partners Inc’s winglets on MSN0001, the same A320 that flew on the last day of November on its maiden flight with the winglets.
This news has come right when I was in the middle of my A320-B738 comparison for fuel burn and other figures. I am glad to have laid my hands on relevant documentation!
A very kind and very experienced Boeing 767 captain sent me a mail with comments on my LOT 767 article, providing his insight into the turn on events on the 1st of November based on his knowledge of, experience on the airplane. His comments shall be posted soon.
My first post in December. I had spent a good deal of the week trying hard to find out the way in which 732 pilots couple their GPS to their SP-77 autopilot. The Boeing 732 has so many variations that its very tough to document this bird.
The A320’s flight with its so called “sharklets” grabbed my attention, as it did others. Whats interesting is that MSN1, the A320 that had the honour of trying out the new winglets, had tried out other types of winglets before. That is for me to document, as is the evaluation of the 3.5% saving against the 737-800 winglet. Friends of mine who fly the winglets -800 will soon be providing me with the relevant data. The aim is to evaluate the fuel burn of the A320 non-winglet against the 738 non-winglet, and then apply a 3.5% fuel saving on the A320 non winglet version over a flight of 3000NM. If this fuel burn is anything better than the 738: well done. The assembly of A320 MSN 1’s winglets may be viewed here: (The YouTube video was deleted by Airbus)
It was interesting to see Flight Com’s offering of a wireless system for wing walkers, the pushback operator and the crew, ensuring clear and quick communications during a push back. It can allow the pushback operator to concentrate on the pushback without watching the wing walkers. while the wing walkers can immediately talk to the operator in case the aircraft is potentially going to clip something. More details may be seen here: http://flightcom.net/solutions/ground-support/marshalling.php
Today was a wild goose chase of 737-200 photos online. I just needed to satisfy my seemingly unquenchable thirst: How did they fly that beast?
Its more about the automation that bothers me. Was their climb profile followed based on charts? How did they navigate when out of Navaids? (I dont remember seeing an INS). How dd they manage without an A/T? There is so much that I need to know, but I dont seem to find any 732 pilot who can satisfy my wild hunger for this info.
Until I stumbled across a promising man, “longhauler”:
I also stumbled across Hemant Bhana, an airline pilot whose written a good thesis on automation complacency. His research is extensive, but the key takeaway points are, well, key. You may read his work here:
Downloaded quite a bit of NASA’s research work on pilots transitioning to glass cockpits. Its an old study: the days when the world witnessed the 767/757 and 737 “Glass cockpits” (Truly, semi glass cockpits).
And again kept scouring through 732 photos, especially those of Sriwijaya Air.
And if you really want to see a good video on the 732, I suggest you see both parts:
Good night folks, I’ve had a brilliant day today! Blue Skies!
I’ve kicked off project “The Cockpit Evolution” (TCE)with a good friend who knows graphic design. Sifting through my huge database, I guess I have enough material; too much infact! And as a result, I need to sit down and order it, chronologically.
Project TCE is aimed at developing a small video: long enough for the necessary details, yet short enough to keep the attention of the viewer. There will be two parts:
The construction of the 737-200 cockpit (Basic): Gradually, we shall “make” the 737 cockpit, from the angle of need. The importance and need for every instrument shall be explained before placing each such instrument/device/system in the cockpit. This way, people would get to understand why the system exists in the first place.
In the end, a complete 737-200 cockpit will be constructed on simple video.
Based on part I, the video will demonstrate how we remove few cockpit indicators and instruments and gradually replace them with more modern instruments till we arrive at today’s NGs.
Project TCE is going to take a hell lot of time, and will see my activity on this webpage sharply fall. I’ll probably come online only when I need a break, but otherwise: Its Project TCE just so that you may enjoy a nice video.
Video shall be non profit and viewable by all.
Wish me luck, guys!
(As I type this, my right index finger is badly swollen probably due to a microscopic foreign object that managed to penetrate my skin while at work.)
The morning was promising: The horizon a golden yellow urging me to wake up for a walk. The time was 0600am at UTC+5.30, and I wanted to catch the sunrise despite my late night due to an excited conversation with a recently Type rated A320 first officer, someone I’d prefer to call a Flying Beauty. It was amazing jotting down her experiences, having come from an ATR 72. The day before, she had sent me a mail that was more like a daily account of her type rating experience.
The excited conversation made me stop her and ask: “Wait, how do you manage your vertical navigation for the ATR 72?”, She giggled. In stark contrast to her new “paradise” A320, where the FMS is worth worshiping, I was mildly surprised to learn that the climb of the ATR 72 is at a fixed 170kts IAS, or 190kts in icing conditions. The power levers are kept in the “notch”, and the power management selector knob at “CLB”. Upon reaching cruise, the knob is rotated to “CRZ”, and the speed that the aircraft stabilizes in cruise is the cruise speed. Descent is on vertical speed, to maintain a speed of 240kts IAS.
Thats it. As simple as that. Isn’t that wonderful?
Ofcourse, such simple profiles don’t give you the best economy. But I guess the actual savings by following a real economical profile wouldn’t be much.
A former airline captain, who had been with Indian Airlines on the HS748s, Boeing 737-200s, and the A320s, before moving onto the 737 Classics and NGs at Jet, had got me his Boeing 737-200 Basic manuals. It was a pleasure (and pain) to have the 10-kg box full of manuals weighing me down! Folders in red, and font in gold made for a nice combination. “dare you damage them” said the Captain of yesteryears.
He was wearing a red checked shirt and blue pants from his Air Deccan days. And his booty is worth a steal! I’ll be going over to his place on the weekend to flip through the manuals of the “Basic” to get a basic understanding of a basic cockpit with basic automation.
As I’m typing his out, I am practicing the ATR vertical profile on a simulator just to understand something so simple that it gets hard to believe.
Woke up to a brilliant morning and a nice winter sun. Winter in this part of the world isn’t snow, but it a pleasant 16 degrees or slightly lower.
Done with my walk, I came back full of ideas. I opened my mailbox, and saw two mails: One from Pat Boone of Boeing 737 “Management Reference Guide” (http://www.b737mrg.net/). I had sent him a mail asking about the Boeing 737 VSD. Few doubts that I had got clarified, and I must thank him for his patient explanation, admiring him for his excellent technical grasp of things.
I had also asked about the Boeing 737-200s, and how flying has changed since then till the NGs of today. Capt Boone has flown all the 737 high level family members: the Originals, the Classics, and now the NGs. His 25 years of flying is something!
I had another mail, and this was from a pretty lady first officer who recently left the ATRs for the 320s, switching airlines. I wanted to understand the Airbus Training as she saw it, including the initial feeling of a fly by wire aircraft that claims to operate in “normal” law but is in effect, abnormal to the uninitiated. Some work to do out there!
Was pleasantly surprised to discover that Capt Richard de Crespigny, under whose command the Qantas 32 that had an uncontained #2 failure was brought back safely to terra ferma, is following me on twitter. Yes, it brings a smile to me.
Manipal Institute of Technology wants me to serve them as a visiting faculty member for avionics. their new Aerospace Engineering department needs someone to do the job well and right. Sitting down to preparing a proposal. Lets see how it goes.
And ofcourse, a nice long bike ride into the setting sun awaits.
The philosophy of Southwest is pretty baffling. Their 737-200s understandably had no auto throttle and a very basic autopilot, that of the Sperry SP-77.
Southwest became, and still is, the biggest customer for the Boeing 737 family. The Launch customers of the 737-300s. 737-500s, (Both Classics) and the 737-700s (A NG), Southwest wanted things its way.
Apparently, because of the desired commonality between the 737-200 cockpit all the way to the 737-700 cockpit, Southwest, until recently, had the VNAV and Auto Throttle (A/T) either marked as “INOP” or covered so that they may not be used. So aircraft which promised better fuel savings through the optimal use of automation couldn’t deliver their best simply because the vertical climb, and the thrust settings could not be automatically managed by the automatics on board. All this despite Southwest being touted as “an industry leader in airline efficiency”.
Today, when discussing the issue with FMS developers, we were surprised why Southwest would have deliberately kept automation off its pilots. Yes, the analog displays on the Classics and the EFIS style displays on the -700s speak of commonality, but was it mere commonality?
Apparently things have changed since a new management has come into force. Auto-throttles (which were always present but never used) helped saved the airline significant money. And with a drive to fly RNP approaches, flight decks have been modernized. Hopefully VNAV has also been enabled, though unlikely.
So with the potential to effect savings with an age old A/T technology and better displays that ensure greater situation awareness, why didn’t Southwest adopt these? Even more thought provoking is that Southwest hasn’t had a single fatal accident. Could the lack of automation kept pilots in the loop?
There are many questions about Southwest that need a decent, definitive answer. Hope the answers come in.
Carried an FMS CDU in my hand. Was a real wonderful experience to be able to do that.
Evaluated Project Magenta’s 737NG software as well. Now that was a shame. Strung a flight of 455NM, and the way in which it constructed the flight path, and targeted speed restrictions was disappointing.
Got sucked into a gripping photo on airliners.net. Do you see something different on the Captain’s ND? Well, it was way back in 2003 that Boeing started offering Vertical Situation Display as an option for new 737NGs, and as a retrofit for the then in service 737NGs. I doubt it has caught on much, but for operators who fly into terraneous regions, this is a valuable tool. Which really catapults the safety value of the B737 in comparison to the A320. Good safety, but the problem: its not standard.
Wonderful real on the article by Boeing on how they went about in deciding on the features of interest. Let me piece something together.
Okay, I was given the task of setting up a flight simulator. “Big Deal” thought I, “I’ve done it 5 times before”.
The architecture was totally different. the FMS was ultra thin. “Whats going on”, wondered I. The control columns were here, the panel displays, but the FMS?
So, curiosity kills the CAT (III?). I was eager to see what was behind the thin little FMS. No name. No marking. No idea who had manufactured the thin little, Smiths like CDU for the 737 sim. Who could it be? Well, lets power it on!
FMS...look closer! (next Image)
And on power up, good lord! Do you see what I see? Can you believe that? Can you?
You better. A marvelous piece of hardware for Project Magenta by Cockpit Sonic. So much for my experience. Caught off guard. totally!
Spent the morning reading up about the history of Universal Avionics. I must admit that I knew very little about this avionics company till I got sucked into the rich and gripping history of a company that’s built on focus, and passion.
If I were there, I would have honestly done no lesser. But honestly, I don’t think I personally may have been able to match the feat of any one of those fine gentlemen who waded the upstream current to emerge as one of the top players in the market.
Market. Universal Avionics isn’t an air transport name. Its more on the regional, and the business aviation front. Suspended between the flooded general Aviation market (ruled by Garmin), and the Air Transport segment (ruled by the majors we all know, such as Rockwell Collins, Honeywell).
What stands out in this book is passion: to serve the aviator, and to better the best. And this focus was not a result of a selfish corporate interest to grab the market and make more money. The interest, and commitment was to make the flight deck better.
The 100 page book starts off with the basics of radio navigation, followed by the need to integrate the various sources of navigational information. This need resulted in the first device of Global Navigation, Inc., the GNS-500. GNI was founded by a pilot, who wanted nothing but the best in the flight deck.
As time went on, corporate turmoil resulted in the formation of Universal Avionics, by those who were “kicked out” of Global Navigation Inc. The grudge and the brilliant few resulted in a smaller company that eventually gained a larger footprint, by thier sheer innovation and strife for excellence.
The book takes on through the various Flight Management Systems, Cockpit Voice Recorders, and Displays that Universal Avionics made. Its rich in its content, appealing to both the casual reader and an aviator, or a systems person, such as me.
When I was done reading, I felt like I was one of them. My love in life is for the flightdeck, and the avionics therein, most notably, the FMS. And Universal Avionics prime focus is on the FMS.
Woke up in the morning to a sms from an ATR 72 pilot asking about the ability of the ATR 72 to fly a GPS approach to minimums.
The question, and my search through my files got me a bit confused. There was no clarity on the viability of the on board HT 1000 to support GPS approach. So I had to head online.
It was a crazy search, but search I did, nevertheless! I found online an Airworthiness Approval document from the UK CAA, which specifies under limitations:
“The GNSS HT1000 must not be used for GPS approaches.”
This question has clearly caught me off-guard, and I’m now trying to understand what makes a non-WAAS GPS approach feasible. And another thing bothering me is whether this approval is only for the specific aicraft: : G-BXTN.
Dr. BR Pai, the former director of NAL, sent me an email requesting me to shed some light on the Q400 vs a turbofan of the same seating class. This was after he read my article on the Q400 vs the ATR72. Now that is exciting! Time to compare the EMB-170, and the CRJ 700 with the Q400. The winner is for sure the Q400, that guzzles lesser fuel, and flies with almost the same sector time.
Spoke to a retired airline pilot today. Capt Frank Elias retired about 5 years back from Air Deccan, after having flown the HS-748s with the late Rajiv Gandhi, the Boeing 737-200s for Indian Airlines, the first A320s for Indian Airlines, The Boeing 737-300/400/500/700/800 for Jet Airways, and the A320s for Air Deccan. Quite something.
So I wanted to know how he used o navigate on the 737-200. Without an IRS, and a GPS that is, while flying over the Bay of Bengal from Chennai to Port Blair.
“Radio Operator. He would fiddle with the radios of the LORAN-C and OMEGA to give us our course.”
And the topic shifted to the PDCS. An Advisory performance computer that would help the crew with take off/climb/cruise/descent figures. They didn’t fly with that coupled to the autothrottle. Was pretty hard I guess.
But he is one in a league of dying aviators: those who actually flew the airplane. Got me thinking loads: Operators of today, stand where when compared to the aviators of yesterday??
Saw some studies on the variation of ISA deviation over distance. We didn’t have the data, so I asked a 737NG first officer from Jet Airways for the same. He gladly obliged, and flew the sector from Chennai to Hyderabad. “4 degrees” came his message post landing.
Wow. And what was the extreme that he has seen? “ISA dev +21, inversion layers upto +35”.
And how the aircraft performs in the light of such conditions: the study was superb.
Got my website domain (www.Theflyingengineer.com) registered today!
And what made my day better? Mark Kirby following me on Twitter! What an honor!
Was engaged with a long conversation of a very long cup of coffee post office hours with a colleague, discussing the difference between aerodynamic stall, and the stall defined as “lift less than weight”. Its kinda funny. How did we come to this point?
Well, the lower stall/buffet margin (that is seen on the PFD as the red and black barber pole) comes up only when the aircraft weight is entered in the FMS. Change the weights and the stall limits change! Now, an aerodynamic stall is independent of the weight, and solely dependent on the angle of attack, and the airspeed. Hmmm!
So the weight entry in the FMS which generates the lower barber pole on the PFD signifies the “stall” defined as lift being less than weight. This happens when, for the same speed and the same AOA, the aircraft banks, rendering the vertical component of the generated lift less than the weight of the aircraft which always acts vertically downward.
We were in a nice discussion about Vmax and Vmo as well. Apparently, Vmo is a hard coded number, but the Vmax is dependent on variables.
Then came a very interesting fact: supposing the ISA deviation goes crazy in the positive direction, and you are at cruise, there can be an ISA deviation at which the available thrust si less than drag! Common sense, yes, but this common sense may not be in your FMS! So, your FMS may actually want you to continue, based on some “assumptions”. Ah ha! Something for you, David Learmount!
And we discussed a lot more on cockpit displays. Wonderful Day. Wonderful talk. Good night folks.